My Growing Area in Steel Cabenit and questions

THe size is 20" deep 36" Wide and 70" tall. I am running a 400W HID come flower time but right now I am going to veg in CFL and may add a MH. I am planning to grow 3 plants in DWC, 2 in the Rubbermade and 1 in a 5 gal bucket, I may go to 3, 5 gal buckets after some advice. I am venting with a 171 CFM fan through a phresh filter blow through outside of the box. Here are my questions:

1. Should I remove the glass on the light to get more air flow?
2. Will I have enough room?
3. Will heat become a problem?

Any comments or critisisms are really appreciated.