Dox, RB is available as a separate purchase it's just if you upgrade to any of the higher level packages it's included. Yes, RB gives you the option to use the first 8 tracks as Biab only tracks so it will generate a complete Biab arrangement if you want. In fact you can start there or just open up an existing Biab song and RB automatically puts the tracks on top and you can still use the other 40 tracks as I described without changing the original but you can have it regenerate everything if you want. This item constantly confuses noobs to RB because some don't want any Biab tracks and the question is how do I convert those tracks to regular sequence ones and the answer is there's a checkbox in the file menu.
As for the styles and RT/RD's, RB will access whatever you have just like Biab will. If you have all of PG's styles and several hundred third party styles, RB can use them all.
Don't get hung up on the quality of the wav's. Mac said it perfectly and you don't know him but he's a working studio pro and our resident expert, you can believe what he says. In fact you should visit his "Audiominds" website, lots of good stuff there. He has the wma version as do I and the audio quality is pristine. Some who have the audiophile version say there's a difference and good for them, most of us can't hear it expecially in a mix but even solo'd they sound great. These tracks are as pro as you can get from the studio equipment and engineers used to the musicians.

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.