You've asked a frequently asked question, which ought to have an FAQ somewhere.
For your specific question about the Gospels, see Ebia's response. He's right that the 4 gospels we have are the only ones that seem to be primary sources for Jesus' life. I'm going to comment on the broader question of whether the Bible is factual.
As for how to best use the Bible for yourself, I agree completely with razeontherock.
If you look at other threads coming from similar questions, you'll see that they end in arguments between liberals and conservatives, because there are two (actually three, but one isn't always Christian) ways to answer your question.
Since the Renaissance, there has been a development in critical thought. By critical I mean an approach that tries to be as objective as possible, asking for evidence and considering alternatives, even for beliefs that we hold dear. The Reformation was right at the beginning of this. Indeed I'd argue that Protestantism resulted when people looked at Catholic beliefs in light of the new understanding of the Greek and Hebrew originals, and realized that some don't measure up. However critical thought during the Reformation was primarily applied to getting a correct translation and understanding of what Scripture said. Since then it has moved in a direction of asking about the accuracy of Scripture itself.
This process is complicated because many of the first uses of critical thought were by people who wanted to attack religion. They felt that the Church (particularly the Catholic Church) was the enemy of humanity, and that it was necessary to destroy its authority. And in the 19th and 20th Cent, critical analysis was used, particularly in Europe, by people who were Christian, but believed that faith shouldn't be based on historical grounds, and thus had an agenda of discrediting the use of the Bible as a historical source.
However you can still try to apply critical thought without such agendas. British and American scholars have been more inclined to do that. They have tended to operate within the Church or within seminaries, and have as their goal simply understanding Scripture as well as possible.
Here's a rough summary of current critical Christian scholars thinking about the accuracy of the Bible:
* The OT historical books seem not to be generally reliable before about Judges. This is based primarily upon archaeology. The creation story is most discussed, because of issues with science. However the problems are not just in creation. They include the exodus and Israel's conquest of the Holy Land, which is unlikely to have happened in the form portrayed in the Bible. By the time of the kings, and probably a bit earlier, it seems generally OK. However even for that period you need to realize that the OT wasn't intended as pure history, but was written to make a point. (Note however that there are a substantial number of archeologists who would go further than this. They believe that the entire historical content of the OT is largely fictional. This is not just a fringe view, as the corresponding NT view is. I'm not yet convinced, but it is apparently a credible position.)
* There are differences between conservatives and critical thought about the intent of some of the other OT books. E.g. I would consider Jonah to be a satire on certain narrow-minded approaches to religion. I doubt that the author intended it to portray as an actual event, and that some of the humor of the satire comes from its absurdity. Conservatives tend to think it happened literally (and thus risk being identified with the view that it's attacking). There are other cases like this.
* The NT doesn't have the serious historical issues that parts of the OT do. You'll read claims that the Gospels are primarily fictional, and Jesus didn't exist in the form portrayed. Those are fringe claims, with little support even among critical scholars. However there are less radical differences on the accuracy of the Gospels otherwise. The "Jesus seminar" was well publicized in its claims that few of the quotations of Jesus were accurate. Again, this was a group whose PR has always been better than their acceptance by other scholars. But that group has more support than those who claim that the whole thing is fiction. I'd say that you can get a reasonable understanding of what Jesus was teaching by reading the Gospels as is, although there are reasons to think that some specific passages have been reinterpreted a bit from Jesus' original. Certainly if you compare parallel accounts of the same even in the 4 Gospels, you'll realize that we don't have a verbatim recording. As a result there are some historical issues, e.g. whether Jesus' ministry was 1 or 3 years. There are also questions about the historical credibility of the birth stories, particularly Matthew's. But in general terms the picture of Jesus' life and teachings in at least Matthew, Mark and Luke is likely to be pretty accurate.
The more serious issues raised by critical scholarship within the NT fall into the following categories:
* Authorship. Of course we don't know who authored the Gospels, but there are traditional associations with apostles. Some conservatives hold views that I think are unlikely (e.g. that the disciple Matthew wrote the first Gospel). More seriously, however, there are reasons to question the authorship of some of Paul's letters, and also some of the other letters. There are different views of the significance of this. Many will say that claiming the authority of someone else for a document was an accepted convention. I'm not convinced. I think it seriously undermines the authority of a letter if it was intended to claim authority it didn't deserve. This would seem to apply to most of the disputed NT letters.
* I believe it's pretty clear that various NT authors had their own viewpoints, and to some extent they conflicted with each other. To pick the clearest example: Both Acts and Paul's letters report that Paul and James were opponents. But both authored letters in the NT. James' letter attacks justification by faith. Plenty of people have understandings that combine the insights of both, so they aren't completely contradictory. But James was in fact attacking Paul. Similarly, Paul has a visibly different approach than Jesus to issues such as sin and judgement. Again, you can combine insights of both, but they aren't always saying the same thing. Critical scholars are inclined to let each author speak for himself, and let theologians look at all of them and try to come up with a consistent position taking from all of them. Conservatives are inclined to paper over the differences and claim that the whole Bible is saying exactly the same thing.
* But the most serious issues have to do with our preconceptions. Conservative Christianity approaches Jesus with the understanding that our sins keep God from forgiving us, and that Jesus' main goal was to die so as to allow God to forgive us. If you approach the NT with this, you can read this into a number of passages. But if you approach the Gospels objectively, you won't find that this was actually Jesus' main message. At least in Matthew, Mark and Luke, Jesus seldom spoke of sin except to say that God was willing to forgive it, and never seemed to see that God needed any excuse to forgive us. What Jesus spoke of was bearing fruit. When he threatened people with Gehenna, it was because they didn't treat each other right, not because of what Christians typically call "sin." For a good presentation of this, see N T Wright's book "How God became King." However this posting is about the accuracy of Scripture, not a full presentation of what Jesus actually taught. There are similar differences in how we read Paul, depending upon whether we come at it with conservative assumptions or not, though I have to say that I'm a bit skeptical of some critical approaches to Paul.
If you reject the critical approach, then there are a completely different set of answers. The Bible is completely accurate in all details. There are a separate set of archaeologists will always find a way to interpret evidence to be consistent with the Bible, and (depending upon how you interpret Genesis) people who will tell you why scientists are wrong about creation and evolution. There are separate Biblical scholars who will tell you that the New Testament means just what Protestant tradition has always said (or what Catholic tradition has always said, if you pick a different set of scholars). Some of these are fine scholars, who really know their stuff. But you'll have to read the Bible for yourself and see which description fits it best.
I think the OT is the editor's best effort at pulling together all of Israel's traditions about its history and its relationship with God, and that they didn't try to pick just one viewpoint. And I think the NT contains most of the 1st Cent material available about Jesus and the early church, and that it reflects the various views of Christians then. But most Protestants think I'm wrong, and that all the books are saying exactly the same thing, and it's completely accurate in all details.
Be aware that the Internet is in general a medium of the popular culture. If you ask Google about most of these issues, the probability is that you'll come up with a pop version of scholarship, which will be conservative, but may well not be even the best conservative scholarship. Wikipedia generally gives you critical scholarship, though it tends to be better on details than on giving you a real understanding of what's going on. The best source, for both conservative and critical approaches, is probably to make sure you choose sources that are from faculty at appropriate institutions -- major universities for the critical approach -- denominational institutions and seminaries for the conservative approach. Bible.org also has excellent conservative scholarship.