Let's start with the easy questions :
A 1 is not necessarily a crit. You get a crit qhen you get spot on your stat.
If your model has
BS 11 and you roll an 11, it's a crit.
If your models has
BS 11, but is in the -6 range mod and the target has cover (so an other -3) you need to roll a 2 to get a crit. (
BS 11-9 =
BS 2)
For the movement, you are right, the second value is used if you are using your second movement
Then for the outcome of your shootout
If my
BS = 12 and I roll 2,5,9,11 (That is 4 hits) My enemy rolls a 8 with a
BS of 11.( So 1 hit)
You always compare your rolls against the opponent's roll(s)
You scored 4 hits but your opponent scored 1. Now you have to compare. His 8 is higher than your 2 and 5 so it nullifies these hits. Your 9 and 11 are higher than his 8, so you nullify this hit.
Meaning you get 2 hits and now he as to roll his
ARM rolls.
You might want to read this thread, I was confused quite a bit with
BS rolls and it helped a lot =)
http://www.dakkadakka.com/dakkaforum/posts/list/442581.page
Do not hesitate to ask questions =)