Domestic rats are nice folks. I've kept a few as pets off and on over the years. Unlike most rodents, domestic rats are disinclined to bite, unless they are actually hurt or severely frightened. I had a friend who used to have many, many, many rats, which she bred to produce new color patterns.
The litter and paper should be fine in your compost.
If you're so inclined, you could give your ratties a little smooch from me.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams