Opinions on equipment+acoustics on large rooms

Hello gurus.

I would like some advice in selecting equipment for playing
music (mainly international folk) to an audience of 100+ people in a large room (60L x 30W x 18H), puplic school type
with cement block walls and no carpeting.
How many watts RMS am I going to need?
What kind of speakers? Any ideas to improve acoustics in such a room?
Would hunging curtains on the wall behind the speakers help?

Thank you in advance.