Realcanman

Just picked one up yesterday a 28" barrel 12 guage. A few questions hopefully you guys can help me with. I want to know what chokes I should use for duck hunting. I hunt a lot of divers and plan on using 3.5" #2 shot. Decoys and pass shoots. I normally have used a full choke in the past. Are the stock chokes the best to use or should I buy else where? The full choke that mine came with says that I cant use it with steel. Also what is the best way to clean this gun (oils and such) thanks.