Veg Room Grow Lights Questions

Hello Growers,

I'll save you the story and give you a quick break down:

My bud room 12'x20'
My veg room 12'x15'
8x1000w HPS (bud room)
Planning on using 4x15-20 gallon pots per light

My questions are what size pot should I use while vegging?
How long should I veg for (baby clone)?
How many lights will it require to veg these 32 plants before switching them over to bud?
Hoods and Watts for vegging?

I'm used to growing in a small space without the ability to scrog large plants. Hopefully you guys can help me out with my new grow!

Thanks,

Mendo Coast Farmer