I would just add that if he is getting hung up on those details he is kind of missing the point. I bet this same guy would swear on his life that the earth is 4.6 billion years old, that dinosaurs were destroyed by a comet/meteor impact, etc. He obviously has 0 proof of either of those "scientific facts". But even the slightest irrelevant tidbit in the bible will be questioned in the hopes that he can find some mistake that proves he is justified in his non-belief.
I suppose the truth is that I am not aware of any proof that the "disciple Jesus loved" is a reference to John, although it seems like a reasonable conclusion considering that I believe the phrase only occurs in the book of John. Note: he did not say "the ONLY disciple Jesus loved" as many people tend to think.
The same goes for the other question too. There probably isn't any proof that would be acceptable to someone who is looking to disprove the bible.
If he is sincere, I would recommend that he read a series of books called "Evidence that Demands a Verdict".
Click here for linkThis series gives all sorts of historical evidence to the validity of the bible and makes the point that the evidence we do have is far beyond what is presented in most court cases.
Sorry I can't be of more help.