If that ammo is corrosive it's imperative and I mean imperative that you clean the rifle immediately after use. The gun store guy should be kicked in the buttocks if he sold you corrosive ammo without telling you that. Corrosive ammo can ruin a barrel overnight.
Other than that you did well. DPMS makes a nice AR, you got a bit of an oddball caliber for an AR but it's plentiful and cheap due to the plethora of AK's out there and if you ever want to use it for hunting the knock down power of the 30 cal round will be appreciated. I would avoid any corrsive ammo, steel cased ammo, any ammo with laquer or moly. I know some guys love moly bullets but in an AR I don't want it gumming up the works. Check out Ammunition To Go : Your one stop for all of your ammunition needs!
and you can buy ammo by the bag full to avoid paying for the cardboard box part of it. AR's seem to be more ammo sensitive as a rule but that doesn't mean you are confined to horribly expensive stuff. Avoid Wolf and Bear ammo. For some AR's Wolf brand ammo is specifically excluded from the warrantee.
An AK will shoot anything at all, the AR is a different animal but better in other ways.