1. Could low compression cause the car to run rich? (so rich that all the excess fuel causes the cat to glow.
2. Is it possible for an engine to have only 70 psi compression on both rotors and still be able to start on its' own?

 

1. Not likely. A bad O2 sensor or misfiring ignition could cause that. Any CEL codes?
2. Yes. When I last checked mine 3 years and 5000 miles ago, I was 68 PSI rear and 72 PSI front. I still have no starting problems (after upgrading to 2 KW starter).
3. This really should be posted in the appropriate troubleshooting subforum, not in "General Discussion". You can ask a Mod to move it.
4. Have you read all the troubleshooting stickies here?

 

Apologies if posted in the wrong forum. Wasn't really trying to troubleshoot, but was trying to double-check what my mechanic was telling me. I'll move or repost.