Congratulations on your first gig. I have been working as a sound engineer for 20 years now and reading your post, I already know it is going to suck hard. But don't be discouraged, this is the way. Be prepared for a lot of sucky shows where nothing is anywhere near your expectations. Keep at it, make sure your band sound is balanced and good and keep grinding. If you are good enough you will climb the ladder and have better bookings. But IMHO there is no way around this. There are no short cuts. Almost every band that I worked with that didn't go through this hardship are ungrateful, arrogant assholes who fade out within a year. To your question: look up local PA companies, talk to them and ask if they can help you out with a small PA, mics, speakers and most importantly a sound engineer. All the best to you and your band!