So…why get rid of the 86 if you feel like the Supra is too much car for you? 86 is the perfect starter car, and it sounds like that’s where you’re comfortable.
At the risk of one of your first exposures to the forum being as bad as mine was - your best bet is to search and come back with specific questions if you need more clarification. People here default to trolling first and helping second, generally.
If you’re looking for measurable differences, a roll bar by itself isn’t it. You’re adding mass to the car with no benefit.
That said, if you’re tracking the car do yourself a favor and just invest in the whole system up front. Roll/ harness bar, Harness, HANS, Seat.
If you’re not tracking the car, there’s no need to upgrade to a Dot 4 or other race fluid. The high temp brake fluids gather moisture faster than the standard stuff and will actually foul faster than regular fluid so you’ll be flushing it more often for no benefit.