Dog food isn't deadly for a cat it's just that the protein level of dog food is too low to meet a cat's needs. A constant diet of dog food would harm the cat's health.

Cash looks like he's nearing 10 years old. The muzzle starts to spread on older cats and their nose starts to get more rounded between the leather and the fur-covered part - the cartilage tends to slowly collapse. Can't see a profile on that nose but after 10 it starts to become more significant

Cats, like some people, don't like change too much. Cash's sleep schedule was probably developed with his last owner over the years but he will adapt to you and your schedule.

He sounds like he just wants to be loved and feel safe.