OP - FWIW, there are two basic ways to go - powered cab with unpowered mixed, or powered at mixer with passive cabs. Number is is probably better, but more expensive. Especially is you are looking at less expensive or used systems, a powered mixer (like what you were looking at) is more likely to be what you will find, and nothing wrong with it. Unless you are playing big places or running instruments through the PA, a sub is more than you will need. Good luck.
OK - enough dirt kicking on both sides. Respect all around, and things will go smoothly. Peace out.