Pet Rat Food Help Please?

I have two six week old baby male rats. They have Small World complete feed for mice and rats for a mixed food along with Premium Mouse and Rat blocks "vitamin and mineral enriched made with corn and molasses 8 in 1" For treats they have Kaitee Yogurt Chips made for rabbit & Guinea pigs but they like them and I was told they were safe for rats is that true? They also have lil buddy snackers pretzels for hamsters gerbils mice rats rabbits and guinea pigs. Is this ok? for their nesting fluff I use Wild harvest natural bedding for hamsters gerbils rats and mice which is made form the seed pod of the Kapok tree. I have found that my rats also love seedless grapes, watermellwatermelonthe seeds out) tomatoo atomatok oil sun flower seeds along with corn on the cob. is this all safe for them. Any other suggestions? Thanks :) also what do you think of this cage http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=23204