Regarding room in your carboy: put a blowoff tube in there, especially if you're fermenting @ room temp. I noticed my first brew (which fermented way too hot) was the only one that actually blew krausen through the airlock.
the subsequent brews, @ 63ish Farenheit, haven't made it to the top of my buckets yet.
Brewing Since July 2012 All-grain BIAB
Primary 1: Raging Irish Red
Primary 2: Lilsparky's Nut Brown Ale
Secondary 1: Skeeter Pee
Secondary 2: Air
Kegged: Two Hearted Clone, Graff, BM Centennial Blonde (again :) )