Don't worry about the not pooping -- he's all cleaned out from the diarrhea, it would be odder if he DID poop right now. He'll go when food has worked its way through his system. (Did you really fast him for a day, btw? Seems like it hasn't been very long since your first post.)
I wouldn't worry about the not drinking too much, either. Greyhounds don't necessarily drink a ton -- I think I've read somewhere that they tend to drink less than other breeds. Add some liquid to his food. If you take him on a walk, he may well want to drink after that.
Greyhounds sleep ALL THE TIME (OK, 90%!) when nothing particular is going on. "Just mostly wants to be on my bed and sleep" sounds exactly like my girl, and she's less than three, healthy, and energetic. How it looks for hours on end in my house: http://forum.greytalk.com/index.php?showto...27s+busy+sunday
He really sounds like he's behaving in a perfectly normal/expectable way for a brand-new dog.