Is there a list of minimum PeA orbits for each planet? (e.g. I use 200km for Earth, 20km for moon)
No, because it's not really a fixed thing. It depends on what amount of stability you need from your orbit. In real life, the ISS isn't in a stable orbit, it has to be reboosted every now and then. Yet if you're a temporary visitor and just circling the earth a few hundred times, you'll consider the orbit perfectly stable.
However, for the purposes of numeric expediency, Orbiter does actually have a cut-off limit beyond which it just stops to calculate atmospheric effects. That limit is noted in the cfg file for each planet, although I do not know the parameter name right now. This might be closest to what you want.
Also, on places like the moon that have no atmosphere whatsoever, the minimum stable orbit is essentially the altitude of the highest mountain... :shifty: