Welcome to our site! Denalli to a Coby will be a "little" adjustment. You will like it. It is a great car for the money and should service you well.
Oil,, everyone has their favorite. I like Castol brand. I shy away from synthetic for the first change and use the onboard oil change indicator. I change around 15%-20% left regardless of miles.
Wheels? Some sites are expensive. Check THIS site and others, like G5Club.net. (Pontiac G5 is the sister car to your Balt). A LOT of folks upgrade from stock and you can pick up some great GM upgrade wheels, very reasonable. Any questions?? Ask away... A LOT of good folks on here!
What color/equipment did you get? You live in Va.? Again... welcome!!
GTO 1
(Williamsburg, Va)