The NKJV is one of many in my collection. It's fully satisfactory - I'd have no problem using it as my sole bible if need be.
Jesus may have spoken in Hebrew, but the new testament manuscripts we have are in Koine Greek. At least some of them may have been originally written in Hebrew, but scholars are divided on that. Either way, we pretty much have to translate from the Greek, because that's what we have. There are also some early manuscripts in Aramaic, known as the Peshitta, and George Lamsa has translated those into English. I don't have a Lamsa translation yet, but I'd like to. The OT, of course, was written in Hebrew... though Jesus and the Apostles, when they quoted scripture, often quoted from a Greek translation of it called the Septuagint.
The earliest translation you're likely to find in a Christian bookstore is the 1599 edition of the Geneva Bible. You could probably find a 1560 Geneva or a Tyndale online if you looked for it. I believe those all contain the same 66 books as current Protestant bibles. Catholic bibles contain 73, because they include additional OT books known as the Deuterocanonical books or Apocrypha.