He looks a lot like Willow, my mouse.
She's 2 years old and still going strong. I keep her in a 10 gal. glass aquarium with about two inches of plain, unscented clay cat litter in the bottom and a good thick layer of prairie hay (cheap to buy, and she adores cutting it up and nesting in it) on top of that. I fluff up toilet paper or paper towels for her to drag into her sleeping area. She's got a wheel and a water bottle, a sort of latticework of pussy-willow branches to climb on, and her diet consists of mixed birdseed (sunflower, safflower, white and red millet, cracked corn) and rat chow, sprinkled throughout her cage in the morning so she can forage the rest of the day. I supplement this with little bits of whatever natural food I have on hand at the time: bits of beef, chicken, walnut, apple, cucumber, orange, carrot, celery, or the seed heads from the grass that grows on my balcony (high up, so there's a low chance of pesticide contamination). I gave her the "thumb" of a crab claw once, and she adored that. Like any rodent, she gnaws like crazy, so I give her nutshells, cuttlebone, sticks, shells, paper towel tubes, and anything else that looks gnaw-able.
Hopefully you'll find something helpful for your own mouse in that huge chunk of text. :p
I don't know about mice, but I know a friend of mine had a dwarf hamster keep three (fairly pudgy) house cats at bay until she came to rescue it.
Poor cats were terrified.