Mixer & Monitors

I'm new to the whole biz of being in a band. We've got a 5-piece band playing mainly small/mid-sized clubs: two guitars, bass, keys, drums. We run the vocals (3 mics) and keyboard through a small unpowered Behringer mixer, the Xenyx 1202Fx (http://www.behringer.com/EN/Products/1202FX.aspx), and out to some powered JBL 15" PA speakers. The guitars and bass all run to their own amps, un-mic'd, and we have no mics on the drums.

We have plenty of volume with this setup for the types of clubs we've played. But, we don't have any monitors and we're not running all the instruments through the mixer and PA so we don't have one point of control over the whole mix.

This has worked sort of okay for us, but it's obviously a very basic set up. And, depending on the placement of the PAs we sometimes struggle hearing the vocals and overall mix well enough, as you can imagine.

What I'm trying to figure out now is the best way to add a monitor or two into the setup. I would need to use powered monitors since we don't have a powered mixer. I also don't know how I would connect the monitors through the Behringer. Any help would be appreciated.

I've also seen some wireless in the ear monitors and it would seem that we could get set up with them for not much more, if any, than buying a few powered monitors. Any pro/con opinions about doing this?

Thanks,
Bruce