Get a live sound mixer that has channels for each mic, inserts and auxes for effects, and get better Mic's.
Those Mic's are basically a Karaoke Mic, 4 Decent wireless mics would cost $2000.00 or more.
Those are like $399 for the whole kit. You get what you pay for.
27" Imac 2.93 ghz I7 12GB ram OSX 10.6.5,
MacBookPro 2.4 ghz duo 4GB ram,
Mackie Onyx 1640I, Motu Ultralite Mk3,
LA610 Solo, Logic Pro 9.1.6 DAW