For your first PA, keep it simple. As you have seen, there are lots of suggestions to go with powered cabs. I am not in that camp, although I concede they are very nice. I suggest keeping it simple. Buy used if you are on a budget. If you don't mind the weight, you can buy good used heavy power amps really cheap, as people are trading up for lighter weight versions. 1000 watts is not as much as you think it is for volume. 300 watts in an efficient cab is as loud or louder than 1000 watts in an inefficient cab. Look at SPL rating on cabs more than watts power handling. I still have and use my Peavey SP2G cabs that I bought 13 years ago. Very good cabs, and cheap used. The black widows are not what they used to be, but can be upgraded easily and cheaply if need be. In my opinion, the used ones made in the US in the 90s are better cabs.
When the time comes, a powered sub would be a good upgrade. The QSC Ksub is killer. They go for about $700 used. I am not a proponent of powered cabs, because they have specialized components that are very expensive if the cab is out of warranty. If the amp is separate and you have a problem with either one, the faulty part can be replaced easily and cheaply with a suitable substitute. As a sub is not absolutely a necessity for a small club PA, I would risk a powered sub. The quality of QSC is also comforting. My buddy, on the other hand, has a JBL powered 18sub that has a blown driver. It's a weird driver that costs about $300. That sub is now a coffee table.
For a mixer, if you can find one with a crossover/subwoofer output, that will be handy if you decide to add one in the future. I don't care for in ear monitors, but they do have advantages. Namely, feedback is really easy to control when there are no live monitors on stage. The downside is, if you let somebody sit in, they will hear little vocals if they are not willing to trade ear wax. I also find it can diminish one's ability to play dynamically, and will disconnect you from what is really going on, on stage. Your actual stage volume should be part of what the audience is hearing. the PA should be used to balance it out, and get the vocals out front. With IEMs, your stage volume could be all messed up, but will be perfect in your ears. One more issue, is the need for more auxiliary sends to allow for individual mixes for each IEM. They are neato, but impractical for me. A bit pricey too. Best of luck to you.
