Crating & Aggression

Hello,

I have just received a JRT for my birthday. He is 8 weeks old and quite the little devil. I have started to crate him since the moment he has come into my home, and he seems to be quite adjusted to it. But how long can I leave him in there. Currently I come home on my lunch hour and walk him and play with him, but I cannot do this every day. Also should I be leaving treats and water in there?
Secondly, he does not want to be crated at night time when I go to sleep, so I've been taking him to bed with me. Is this okay?
Finally my last question is this, my little guy is starting to nip and I give him the two minute time outs
but it doesn't seem to be working. Do you have any other suggestions?

Thank-you in advance for answering these questions.