Welcome to TCL, JesusRocks4Me!
I'm glad you're here.
1) If God has a predestined elect, how can they fall from grace? I know Lutherans believe in very Calvinistic single predestination AND that Christians can fall from grace. How can the elect fall?
Well, first of all, it's not exactly accurate to say that Lutherans believe in a very Calvinistic single predestination. I'm going to quote below from
A Summary of Christian Doctrine by Edward W.A. Koehler. This book has been used as an introductory text for our seminaries, and it is excellent:
We believe the Bible "teaches that God will have all people to be saved (I Timothy 2:4) and that the person alone is at fault if her or she is lost (Matthew 23:37, Hosea 13:9)"
"Human reason cannot harmonize the two doctrines of the Bible, namely that God by grace for Christ's sake will have all people to be saved and that God by grace for Christ's sake elected few to be saved. The two cannot be harmonized. We can only restate what God has revealed to us in His Word. We cannot begin to guess what He has reserved in His hidden wisdom concerning this mystery. God has not revealed to us all He knows, all He did and intends to do for our salvation, nor His reasons for His acts. But God did reveal as much as He wants us to know and as much as we need to know regarding salvation through Christ. God does not satisfy our curiosity concerning His secret counsels. Therefore, we say with Paul, "Oh, the depth of the riches both of the wisdom and knowledge of God! How unsearchable are His judgments and His ways past finding out! (Romans 11:33)"
Calvinists make the mistake of applying human reason to divine mysteries. If taken to its logical conclusion, this erroneous way of dealing with God's Word cannot help but lead to the false doctrine of double-predestination. As Lutherans, we are comfortable with mystery. We believe what God says in His Word, even when it does not fit into our human scheme of logic.
As to how the elect can fall, I found an excellent discussion of that here:
Is a Christian "Once Saved Always Saved"?
2) Why do Lutherans do confession? It seems...idk. I thought only Jesus had power to forgive sins.
John 20:21-23
"Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending you.” 22 And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit. 23 If you forgive the sins of any, they are forgiven them; if you withhold forgiveness from any, it is withheld.”
Matthew 18:17-18
17 If he refuses to listen to them, tell it to the church. And if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector. 18 Truly, I say to you, whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.
Jesus gave authority to His church on earth to forgive and retain sins.
One of the things that used to mess with my mind about confession and absolution before I became Lutheran was that I wondered how on earth the Pastor could know whether or not a person was sufficiently repentant to "merit" forgiveness. Only God knows that, right? I mean, what if someone was just standing there saying the words of confession, but didn't really mean it in their hearts? How could the Pastor pronounce God's forgiveness to them?
Then one day, I was meditating on this passage of Holy Scripture:
Matthew 18:21-22
"21 Then Peter came up and said to him, “Lord, how often will my brother sin against me, and I forgive him? As many as seven times?” 22 Jesus said to him, “I do not say to you seven times, but seventy-seven times."
How sincerely repentant do you think a person is who commits the very same sin against you
77 times in a single day, and each time comes up to and says, "I repent"? And yet, we are commanded not to judge the person's sincerity, but to forgive them freely. God is so much more merciful than we are, and forgives even more freely than this. The Scriptures tell us that if we but confess our sins, He is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
Upon our confession of sin, the Pastor declares God's forgiveness to us in Christ's stead and by His command -- not because of the worthiness of our confession, but because of the love of Christ shown in redemption He has freely provided for all in His death on the cross.
A Pastor who says to us, based on God's Word, that our sins are truly forgiven us, is a great comfort to consciences burdened by sin. It is a gift from God to be able to hear the comforting words of God's absolution and love.
Besides, you Baptists essentially practice it, too! You just don't officially believe in it, you don't call it confession and absolution, and you only do it once -- when a person comes to faith. I'll bet that when you walked the isle and prayed the sinner's prayer that the Pastor told you that all your sins were forgiven. He was basing what he said on the Word of God, and so are we.
The difference is that we also take Jesus at His word when He says, "If you forgive the sins of any, they are forgiven." And we get to hear those comforting words every week, and not just one time.
3) What is the Lutheran position on dating/marrying someone of another denomination? The girl I'm talking to is a United Methodist.
I'm not going to give you the "Lutheran position," but rather the position of someone who's been married 23 years. It's not wise to marry someone who does not share your beliefs. Thankfully, my husband and I do share our beliefs, but I have known other married couples who didn't agree, and it can make for some very difficult situations, and a lot of marital stress. It's hard to go anywhere in life when you're pulling in two different directions. I think the New King James version of Amos 3:3 captures this problem well: "Can two walk together, unless they are agreed?"
4) What would I do about church while I'm at college? The nearest LCMS church is like an hour away. I can't drive that far on Sundays. Close enough to drive are Catholic, Baptist, Presbyterian, United Methodist, non-denominational, and Christian Churches.
I think the important thing right now is not to think in terms of practicality, but to continue to search out the truth. God will work out the practicalities.
Hope all this helps in some way.
They'll either destroy your faith or leave you believing in almost any silly theory that comes down the pipe!
I can't go into any details here because discussing it openly causes problems. Just do yourself a favour and stay away from ELCA! Frankly, I'd rather see you go to a Baptist church then... them.
Episcopalian can be a problem too. The American version of the Church Of England has some serious issues. 
