It's got a wealth of content, my RBR folder is 100GB. Given that the game is from 2004 and assets back then were probably 1/10th of the size they are today, that's a lot of stuff to do.
It supports everything you've stated, almost out of the box. There's less fuss, and more success, getting modern hardware to work on RBR, an ancient title, than there is getting anything to work in Forza Horizon 5. An indictment on game developers today. If a game from the the first few years of the DECADE can do it, there's no excuse.
I will give one tip. Give the Rallysimfans.hu mod a try if you like RBRPro. They have a very similar approach to the install package, leagues for competitive timed runs, etc. but are still very much constantly updating to this day. I've had 4 or 5 updates since installing it at the start of the year and it includes physics updates, additional rallies, cars, sounds, all sorts. Not sure how active the RBRPro mod is in development these days but that's another system you could try if you like it. A lot of it will be the same stuff, but it's an option to be aware of. As far as I know, there are like 3 or 4 different active mods for RBR and all are maintained by different people. There's the Czech mod, the Hungarian mod which is part of rallysimfans, I think a French mod as well. There's a few.