Well I’m already disqualified since you asked only for opinions from Direct experience with SVS’s ultra surrounds, but still feel some general info/opinion can apply.
1. The bookshelf is spot for all locations. Unless a room is horribly small, nobody should use bipoles.
2.prime towers could work as all SVS speakers are voiced to mix n match with each other while maintaining budget if necessary. However, while they wouldn’t not hinder performance directly, they will be too low for “regular” surround duty. They would be the right height for bed speakers in an atmos system, but most will say they’re overkill for surround duty. This depends on your own philosophy. IMO, you should not skimp on rear speakers if you can help it.
3.yes, this would work pretty well.
4. IMO, yes. This is only my opinion, but bi/dipoles should disappear from the earth. Also, I don’t believe in the dual speaker option in the ultra surrounds. Sorry...
Also, if interested in atmos, Dolby says NOT to use bipoles. The imaging accuracy of monopoles adds to the 3d sounds effectiveness.
5. Depends on many factors, such as placement , and room size/shape. I have 7.3, and while native 7.1 tracks are rendered very nicely, 5.1 or 5.1.4 can absolutely be satisfying and killer. If you don’t have at least 5’ behind the LP 7.x anything isn’t effective.
Hope there’s something useful in there...