Interesting questions! Maybe the EPR does change. Never been looking at it to notice. On the Boeings I've flown, autothrottle sets the required thrust and i haven't been aware of it modulating the thrust levers to maintain constant thrust. I think any change on big fan engines must be very minor.
Question 5- back in the 70s I was dragged out on standby to copilot a Certificate of Airworthiness test on a VC10 fitted with an AoA meter. Following the incidents of superstalls on Tridents and BAC 1-11s (always fatal), I was not altogether happy to find myself doing stick pushes at 15,000' over Anglia. Speed was reduced to below 100kts and AoA hovered at 15 degrees, then twitched, then jumped to 17 degrees. The stick push horns cut in and the stick was pushed forward and suddenly there was a nice view of farmland. Nice to be alive and enjoy it, but Notso couldn't help thinking 'very good theory, but what if it doesn't work?- I'd really rather be home reading the Sundays!' Back to your question- I assume if you stalled in a bank situation (increased 'g'), I think the AoA would be different?
To expand slightly on INS & True North, systems cannot sense the direction too near the Poles, so INS sets, although they can fly over the Poles, cannot be aligned preflight near the Poles. I forget the limitations, but I think if a 747 started out within about 20 degrees latitude from the Poles, the INS sets would have difficulty aligning themselves. Used to take Classic 747s about 20 minutes, the 400 version about 7.