Which Macbook should I get?

I'm starting into the film editing pretty hardcore, I've just enrolled in some NYU Film Academy camps and slowly trying to break away from my PC (even though its hard because i'm a gamer). I'm content with keeping my PC for gaming (like WoW and Sims) so that won't be the issue! But I need a Macbook Pro for things like Final Cut Pro and all the special effects programs. I know everyone uses a Mac so I just need to know which one will be good for me? Ram and Space wise. I'm planning on using an external hard drive to keep all my video files on so I don't crowd my computer but that being said I still need a good amount of space. And I really want a bigger screen (mine is 15 inches right now) because that is what I'm used to. But price wise does it just make more sense to get the 13inch? Help me out guys, I'm new to all this!