what about the subdecimals of potential, HoF specifically 10.00 to 10.99, are you able to estimate what salary/tsp is needed to hit the cap for let's say, 10.50?
No. There are many skills which do not affect salary in the different formulas but still do take up some potential space. In other words you cannot directly bind salary or TSP to potential space.
You can use the calculator in BM, which gets it decently close but do keep in mind that it does not account for sublevels.