Yeah, 4x4 would be perfect, think about ventillation, and you could probably pull 8oz being your first time and all. Bagseed is good to learn from, but having different strains within that bagseed is a bit difficult.
A little tip:
Keep it as simple as possible!
Don't start splitting up whose who's until everything is dry and cured. And don't tell you friends what's going on, they'll want some.
If you plan on growing in the same space over, and over, you should think about setting up a small cabinet, or closet for mothering/cloning.
Good luck, keep growing.