A big old hob can obviously take more abuse from a rat than a little jill could, but it depends on the size of the holes etc as to what you can use. If possible, avoid ratting with them as its pretty risky tbh.
Pretty much any meat (or tripe) is ok to feed 'em, as long as you know its safe (no infection/diseases etc. visable) but if you mean like canned dog food, then no. Its pretty bad for them altogether and doesnt give them the right nutrients.