Melee combat is okay, if you're looking for a zombie came with good melee combat look at Dead Island. The combat in Dead Rising is more about using crazy weapons, you literally can kill zombies with anything you see from bats, blades, umbrellas, lawnmowers, dildos, chairs, guns, chainsaw, spears, and a ton of ridiculous weapons. Also there is a basic weapon combination system that will allow you to make some odd weapons, one of the combos results in a lightsaber.
Protagonists don't really matter. Dead Rising 2 is slightly more serious than Off the Record, but the series is not meant to be serious at all. Frank West starts Off the Record as a former photojournalist that has become a washed up reality tv star after the events of the first Dead Rising, whereas the protagonist of Dead Rising 2 Chuck Greene is a motorcross star taking care of his infected daughter.
Coop is not required, but it makes the game a hell of a lot more fun if you're playing with a friend. All it does is drop another player into the game and causes no change in the story. If I remember correctly coop is the same in both games.
