el_goodo_maximo said:
For speakers what's the difference between a 12 and 15 inch? I know a 10 inch has more highs. But is one of these more desirable?
I'd be more inclined to say 10's have a more
mid-range/treble-y sound than 12 or 15's. Most PA speakers have a horn or tweeter assembly so by going up to 15's you're gaining some bottom end without sacrificing highs (which you will want for acoustic guitar and vocal clarity). It's a generalization, but the bigger the speaker, the more power you can run to them. If you're playing good ol' R&R in a medium sized club, I'd go with the 15's just cuz

If you're doing a little coffee house "unplugged" type gig, a couple hundred watts through 12's would be okay. If you plan on running bass thru the PA, make sure your speakers are appropriate for that use.
Figure out what you want/need for a mixer (number of channels, power/wattage, features like effects loop, monitor outs etc.) then choose your speakers to match to handle both power and Ohms (very important). 2 and 4 Ohm systems are good, 8 Ohm ones are bad, though I can't remember just exactly why - something very scientific and technical that someone here can expand on I'm sure
The head style mixer/amps are good for convenience and portability, otherwise you're likely looking at a mixing board and seperate power amp(s).
We run a real mixed bag of Peavey, Behringer, JBL and Yamaha - mixers, power amps, cabinets, subs and monitors - so no real preference here, though if pressed I'd still be partial to good ol' Peavey. That shizit is just rock solid, man

And you can usually find good used gear locally or on the 'bay. $1000 bucks will probably buy you a pretty good little used PA.