1. If a PSU is being pushed to its max power output (90-100%) what kind of consequences will there be?
2. Do newer Nvidia graphics cards have the ability to automatically lower their power usage if there is not enough power for them to use? (Palit GTX 650 Ti OC)
3. Do stutters while playing games show possible signs of the PSU being too weak?
4. If the computer gets a BSOD, does that mean some components just got permanently damaged?
I hope this is not too much for you to answer.
1. Most "good" PSUs will handle 100%-120% of their rated output. Good PSUs will automatically shutoff, bad PSUs will crash and burn, potentially taking part of your system with it.
2. No. It's not possible for any device to know how much power is available to the entire system. Devices will simply draw whatever power they need and the PSU will either provide that power stably, provide it unstably (can cause crashes), or not provide it at all (shutoff).
3. No. Freezing while gaming may be a symptom of inadequate power delivery, but not stuttering.
4. No. A BSOD occurs when something happened that shouldn't have happened but there are tons of things that can cause BSODs including driver and kernel bugs. If hardware is damaged it's likely that the system will become unresponsive, not undergo a soft failure as with a BSOD.