Every belief system or philosophy is heretical to some other, otherwise it would have no cause to exist. This does not make all of them equally valid.
As to #1, which might be of interest, how are we to know since we don't have the original text?
If you will research the issue, you will find that the textual integrity of the Bible is perhaps the greatest of any work of antiquity known to man. The only truly "questionable" portions are clearly delineated in translation and have no significant impact on Christian theology as a whole (for example, the episode in John regarding the adulterous woman). The fact is, that there is little doubt that what you have before you is the genuine article. I recommend Josh McDowell's Evidence that Demands a Verdict which opens with a fine overview of the subject.
We don't have the original text.
Exegetes would be unemployed.