1. I have upgraded a few of my ships, do all these upgrades available come with the respective ship? E.G Darth Vader in the Lambda class shuttle? If you go to http://xwing-builder.co.uk when making your squads it will tell you what the upgrades are from

2a. What is a good size playing area for a 100pt game? 3x3, 2x2? 3x3, 2x2 is quite small really and you cant get the full manoeuvrability and best out of some ships

2b. What is the largest amount of asteroids i could possibly need? Normally its 6 which come with the starter set, that's what it is in standard and tournament play

Just looking at your squadron and assuming you want to stick with those ships atm, how about

Chiraneau with Rebel Captive and Predator
Academy TIE x2
Omicron w Vader

100

Imo Chiraneau has a better ability as Oicunn is quite situational and Cs one can be used every turn really, I got rid of Gunner as you already have Predator and I think its a bit redundant