Danny, Ryzard is absolutely correct. I completely understand what you're doing and you don't need any of this stuff unless you simply want to have fun at home.
Some of the suggestions are overlooking your requirement list such as using Real Band to create some Real Track's or Drums. That's fine and it will sound great because I can tell you know what you're doing but on your list is the item you want to be able to do quick tempo or key changes on the fly. Those RT/RD's are audio files guys, you can't do that in RB without regenerating the tracks first and that takes too long on a gig. To do what he wants requires everything to be all midi. RB can create absolutely killer sounding Mp3's that can be used on a gig but then he loses the ability to make all those different loops and other things live.
Anyway Danny, go here Norton Music Notes is a complete pro, does the same thing as you plus he made a pretty nice business out of it. He's created literally thousands of very good styles and a lot of them are designed to work as covers. Because of your point about having the song sound as close to the original as possible, he doesn't use any of the RT/RD's. He has some very detailed articles explaining exactly how he uses these things live on stage. You can also do a forum search under his username Notes Norton, he's posted on these exact points many times.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.