p.1 #2 · Any way to quickly disable touch to focus (A6500)
If you have a Sony alpha camera and don't ever use the touchscreen, just turn it off. The touchscreen only allows you to pull focus, and it doesn't do a great job of that anyway. Turn off the touchscreen on the the a7iii, A7Riii, and any other alpha camera with a touchscreen if you're sick of it focusing in the wrong places.
p.1 #3 · Any way to quickly disable touch to focus (A6500)
This is why RTFM came about. Don't have a A6500 but guessing it has that capability. Go into Function Menu Set, and look for 'touch operation' to assign to a position. On my a7r-IV its located in the Setup window 14/15, most likely a different page number for the A6500.
p.1 #5 · Any way to quickly disable touch to focus (A6500)
I think the touchscreen toggle by default is the delete key on Sony cameras, though I'm not 100% sure as I'm still using two that don't have touchscreens.