I use KAYTEE clean and cozy natural bedding, I used to use aspen but the dust made Momo itch and bothered my sinuses. I'm sure a number of people here will disagree but I feed him kaytee hamster food as well and he likes it and is healthy. But I also give him carrots now and then other vegatables are good as well.
As for treats I give him drop treats by all living things. As for toys stuff to chew on are always needed, toilet paper rolls they like, a wheel (I'm sure you know this), and I also usually put actualy toilet paper or tissue paper in his cage so he can shred and make bedding out of.
If you have any more questions just ask and I'll answer if I can.:)