could have bent valves and it progressively got worse, but doubt it. Need to do leakdown test to be sure.

Do your RPMs jump around at all? Sounds to me like your distributor is going out, that will def cause the bogging and sluggish feel. Its easy to fix, just swap to a friends known good dizzy and see if it changes. Most likely its the ignitor inside going bad. The tach will jump around if it does it.

As far as cooling, shouldnt hear any noises at all. thermostat is way to quiet and doesnt work like that. Replace it, $15 cost. If your car is staying cool, it could be from the thermostat being stuck OPEN.

Only waY thermostat causes compression issues is if you have a blown headgasket