Vocals!?

So, my band's singer left recently. and I am now stuck with the lead vocal position as well as keyboard and guitar.

I now have no means of amplifying my voice, my bassists voice, and my keyboard.
I need to go out and buy a P.A. or multichannel keyboard amp to run vocals through primarily.

I have no clue what type of amp would best suit my needs. I'm looking at a 500-800$ budget. My band plays mainly Ska, Rock, and Indie, so I need an amp that's loud and clear sounding. I'm looking at a Roland KC-550 right now. Something fairly portable would be prefered. We play mainly smaller gigs, but we like to sound real full and loud.

Can anyone help me out or give me any buying tips. I'd really apreciate it, Thanks.

Strings

My name is Ryan, I've been playing guitar for about two years and am beginning to take my playing very seriously. I have developed a sensitive ear and am starting to explore my string options. When I began playing I used any brand of .9 strings. I am currently using .10 Ernie Ball. I play on a Gibson SG Faded. I play mainly Indie and Hard Rock. I'm looking for that warm full Gibson sound.

Which strings brand would you suggest?
and what are the differneces tonally between brands?



I would experement to find my own preference, but it will cost quite a bit to purchase all the different brands.


also... I may be purchasing a Fender Stratocaster soon. Which strings do you think would suit a Strat for a nice bluesy Hendrix/SRV/John Mayer type tone?