Thanks fam.
The fact that most rappers don't know what you just listed is the exact reason why a group, or any rap artist for that matter, can benefit the most from a producer. And my project is a rap album, it's a concept album, musically it's 99% live music but we aren't a band and I vetted each person before they contributed. We sat down, I told them what I was doing, asked how they could contribute, showed them the business plan, told them if they worked what was expected, etc. From there they would get drumlines with one instruction: "if you vibe to it cool, lay down a scratch track. If you don't then I'll send you another so scrap it."
So what made it easier is the ability to communicate and express my needs. Having a background in engineering helped, background in production helped and having an older brother who helped pave the way for the Vallejo rap scene helped.
Personally I would try to record at 88.2 but 44.1 or 48 works. Point is, and I agree with you, don't do mp3s if you are going to master. And to add to that, if you do master leave a bit of headroom (-6db to -3) and let a mastering engineer, not a mixing engineer, master the tracks.