Help with 2x4 COB tent

I've lurked on here for a long time, so I'd like to thank everyone on this forum for the excellent info.
I'm planning a new grow with COBS in a 2x4x5 tent and have some questions.
1. What premade COBs would you recommend for this size tent?
2. I only have experience with HPS. What is different with COBs in terms of room setup(fan/filter size, required CFM)?
3. Is there any difference in feeding?

I just made the switch to cob this last run I'm in a 2x4x7 tent. I have the timber 400w verov7 and honestly I would go with the smallest exhaust fan you can get with a fan controller cause they really don't produce that much heat. Running full blast my temps don't go over 82/83. As far as feeding that's going to depend on the plant. Best of luck n happy growing.

Thanks for the info. If you don't mind me asking what were your yields like with that light?

Also what exhaust fan are you using? And are you using a filter?