Okay, about my first 3-gun match, what will I need?

I have:

Carbine (you saw it in the '44th' thread)
1911
870 (18" barrel, side saddle, Knoxx stock, Hopson sling)
Drop leg rig for 4 AR mags on my left hip and 1911 holster on right (does me well in carbine class)

What will I need to accomodate the shotgun?

How much ammo for each will I need?

Many thanks in advance!