answers
1)
I am doing the same thing. It is impossible to get tickets. It seems that you can get minor errors corrected even at POE. In any case - one day should be enough. It is impossible to anticipate every possible contingency, obviously.
2) I got it in the same format as mine...job, salary, "to continue permanently after GC etc.". That\'s the logical thing according to me.
3) Emp letters are valid for 6 months according to Ron Gotcher on Inninfo.com. Not sure about I-134 but I think it should also be valid for a few months. I am doing mine Dec first week.
Our interviews are on the same day. Shoot me an email if you want to touch base.