Well, actually, from this list I have only driven in Austria, Croatia, and Montenegro. I hope to add a few more places this summer also, but haven’t yet. So I am not much help with the questions you have.
Tolls in Croatia were simple to pay at the toll stations. Albania only has one or maybe 2 toll roads, I think, and you might not end up on one. Montenegro about the same. Serbia has more. I think with the scope of this trip, tolls are not a huge concern.
My biggest concern about this trip is that you have 10 stops in 9 countries. Someone must love the planning process even more than I do - that is a lot of preparation, along with a number of different currencies and cultures. You didn’t mention how long you have but I do hope it’s a couple of months. With only 3 nights per listed city and no stops in between, you have a month of travel.
I have not checked this myself but it might be that you can’t take a rental car from Austria into Albania. However I know my daughter rented in Tirana and took the car into N Macedonia and Kosovo with permission and appropriate insurance. But she also returned it in Tirana.
If you run into issues, you could look at breaking your trip into parts utilizing more than one rental car, plus some busses/trains/ferries/flights - especially if you don’t have a lot of extra time to spend some nights in other towns in between your mentioned stops.
Its a long drive Vienna to Split, so I might be tempted to take the 1 hr 10min direct flight instead. Then ferry Split to Dubrovnik. You could bus to Kotor (and all along the coast) if you can’t take a rental car from Croatia or Montenegro into Albania, etc.
I would also suggest stopping in Pogradec or Korcë on the way to N Macedonia. Albania is fascinating and you will be missing most of it.
This is a really ambitious trip - it could be extremely interesting, but also more difficult than you think to put it together. Vienna seems like your outlier, so think about flights - and brainstorm transportation combinations if you run into car permission problems.
I would love to hear how this goes (and how the planning progresses), so I hope you’ll check in as you plan - and then report on how it went afterward!