Yeah, I'll have to agree with the other guys- there's no one-stop-shop for what PA to buy.
However, for what you've described, here's a couple of tips:
Hip-hop shows will usually require wireless mics, and those mics should (at least) be
Shure SM58s. Do to the high-energy performance, there's a lot of heavy breathing, a lot of movement, a lot of everything that you really don't want to have. The 58 has good internal pop-filtering, and a wireless version will stop your artists tripping over themselves and destroying your cables. Of course, the 58 is a baseline, you can always experiment, but it IS the industry standard for a reason... You should be able to pick up a couple of UC (wireless) models- they usually suffice for the smaller gigs, and, whilst they don't have the greatest reliability, they are a bucketload cheaper than buying a new ULX or SLX system...
Monitoring for these gigs is a synch- in-ears. There's so much crowd noise at some of these gigs that you're mad to go otherwise. Sure, you can chuck a wedge in front of the artist to give them a bit of "feeling" for the sound, but the isolation and clarity offered by in-ears is phenominal. HOWEVER in-ears require a really good monitor engineer (that's another point, if you're serious, and can afford one, get yourself a seperate monitor engineer). You will also find the artists much more willing to accept the in-ears if you put a "crowd" mic near the front of stage, then play that into the monitor mix at a lower lever; this maintains the "connection" to the audience that makes these gigs go off. Without the crowd response (which is lost due to the isolation of the in-ears) the artists feel uncomfortable, leading to a shit show.
DIs. Well, any really. I know I shouldn't say that, but, at the end of the day, at a hip-hop gig, you're not going to notice a bit of transformer noise amidst the music and the lyrics.
As for everything else you've asked for, like the others have said, it's very venue dependant. I once used a 50kW/side system on a crowd of about 600, then, the next week, used a 10kW/side system for 800 people. The only real way to learn what you need where is experience. Call you local tech(s). See if you can work in some local venues that do similar gigs to what you want to do. Ask people questions- check out people's gear. If you're at a venue, and it sounds crap, take note of what they've got, and what exactly sounded crap about it. If it sounds hot, then also take notes.
But, most importantly, ask people questions. Sometimes they'll be reluctant, espically after a hard gig, but you don't know until you try. And these forums are a good place to catch people when they are most receptive.
Hope this helped you, if you've got any more specific questions, please don't hesitate