Welcome to the forum from me as well! I can't answer all of your questions but maybe some.
I'm pretty sure with the versatility of the Kemper you should find all of the tones you need. But if price is an important factor for you, I'm not quite sure it is the perfect solution for you, as very good tube amps can be had for well under 1000 bucks and for a Kemper you have to pay well over 1000 bucks. Which amps exactly would be a good match for you I can't tell (because I have no clue), but maybe someone else can help out there. At this point you will have to weigh your options: pay more for higher versatility, consistency and convenience or go with the lower price. And this decision you will have to make yourself
If you were to decide on a Kemper: a FRFR is an perfectly accepted solution and real cabs are mostly (there are exceptions here everywhere, obviously ) used by people who want the same live feel they had with their tube amps. Since you are accustomed to digital amplifying I think you should be fine with a FRFR.