My first thought would be a 20ga SxS for quail...nothing finer than shooting those birds with a nice double. However, $500 won't even get you the stock on a nice one.

The glaring omission I see on your list is a medium-bore, bolt action rifle. How about a new Ruger Hawkeye in .338 Federal? It will make a splendid deer rifle, and you'll be set up perfectly if you ever get the chance to hunt elk or black bear.