1) So far there are 5 comics. There is the 4-part “Legion” miniseries and a comic convention exclusive, “The Zeddemore Factor”. The confusion may come from the fact that there are many different covers for the different issues of “Legion”. Here's the list:
“Legion #1”: 6 covers
“Legion #2”: 2 covers
“Legion #3”: 2 covers
“Legion #4”: 3 covers
“Legion” along with a colored version of “The Zeddemore Factor” (it was originally in black and white) are being collected along with bonus material in a hardcover edition that is soon to be released. Pre-orders for that have already closed, and they are only printing the number of pre-orders they received. Your best bet would be to ask your comic shop if they ordered it and if they did to save one for you, or order from
GrahamCrackers.com (you can also order the other issues there as well).
As for the influence on the comic, it is definitely more movie based. The guys act more like adults and have more sophisticated humor, instead of the childish RGB stuff (not that that's bad). However, there are a few influences from RGB, like the containment unit. Everything else is basically all movie based, at least in my opinion.