read is the best thing to do, go through the faq, or go through threads here, most info is here, good authors are greg green, dj short,soma, ed or mel, ect ect ect

it would be ideal to use the 4' fixture but you will probibly be more efficient with an over head hanging light, maybe use lightbulb sockets and cfls worse case senerio, or get 2' fixtures

paint everything flat white paint or use a mylar reflective material. use 5000k-65000k for veg and 2700k-3100k or so for flower. you can grow the plants right up to floroscent lights but its best advised not to touch the bulb

it will be best to use seperate rooms for the different stages of growth

being such a short heigh i would look up scrog, sog(flowering rooted clones),lst and you should be on your way