sounds like a fantastic setup in there mate! only thing i would say is make sure your closet doesn't get too hot so pleanty of ventilation! and second, i would get some CFL's, they have the perfect spectrum for veg, save you money on electricity bills and reduce heat per watt.

for an 8' space you obviously want plants about 6-7' tall, leaving some rrom for lights etc. howevery taking a plant this tall can be a little tricky but nothing to worry about really! remember a plant can double or tripple in height during flower so for our first grow try veging to about 3' and see if it fills your room, 3' should take about a month and a half to two months under the right conditions.

as for strains i would say avoid low ryders cos you've got the space to go tall meaning more nodes which means more bud sites which means more yeild! just try different strains but i started with outdoor strains for my first grows as they are more resiliant to any mistakes youmay make!

yeild... lol, who knows? but inthat sort of space with 3 females, maybe a bit of LST or SGROGing ou should do pretty well my friend!!

peace!