I am just entering my second season with Nephrurus, so I am not an expert. From what I have done and from what I have read:
1,what type of container do u brumate them in? Brumate in their normal enclosure. I use 32qt tubs in a boaphile rack
2,what do u do to supply them water during brumation? Spray the cool side under the hide once a week just like you normally would.
3,3 months is the usual brumation time , correct? Yep.
The only few tips are:
1.) Make absolutely sure their stomachs are completely empty before starting brumation. 2 weeks of fasting should be sufficient.
2.) Be sure the room gets cold enough. I have had a hard time in Southern California getting my room below 75*F and A/C is a requirement for me. If the animals get into the 75* range I have noticed they are not put down far enough into brumation and will burn up their stored fat. It seems 65*F is about ideal, with some fluctuation being acceptable.
Good luck!
Jordan Russell

www.californiabreedersunion.com