You usually can in small amounts. Definately try giving your rats a very small amount at first to make sure they don't get really bad diarreah. All rats are somewhat lactose intolerant, but to differring degrees. I give my rats yogurt and cheese and they are fine, but I've known people who's rats ended up bloated with diareah so it's up to you if you want to try. Starting with a tiny amount is pretty safe though.
They do love milk products! Mine go nuts for "Yogies" (yogurt drops, either made for humans or rats.) Also, as an alternative, you can give soy or lactose free yogurt, milk, and cheese. I give my rats yogurt baby cereal with soy milk. Hope this helps :)
You can give it a piece of cheese to snack on. Honestly I don't think cheese is the best snack for a rat. I'd rather give it yogurt or sunflower seeds. That is what I always give my rat to snack on. So i guess you can try all three yogurt , cheese , and sunflower seeds and see what it likes.
This is a blue fancy rat: http://www.freewebs.com/rattyloving/Anyaonrocks.jpg
The way to exercise your rat is to buy it a spining wheel and see if she/he will run.
no
This is a blue fancy rat: http://www.freewebs.com/rattyloving/Anyaonrocks.jpg
No
Yes.
Rattus norvegicus
No, dumbo rats are much bigger than fancy rats. They are both very nice creatures though.
fancy mice
I've Seen A Lot Of Pictures Of Carrots In Fancy Rat Cages.
No rat is really "the nicest". it all depends on how much you play with them and toys in their cage. If you are looking to buy one, my personnal favorite is the fancy rat.