Ok, I did wires hack on the knock sensors harness. It's easy search on YouTube.
Been a while, works fine. Took about 15 min, vs taking apart half engine.

 

Not correct. You can drive very fast in limp mode, right up to the redline. Speed is only limited by the RPMs, as limp mode on these just disables going into overdrive. I just went through this, but I have it fixed now.

 

Fail-safe mode does different things depending on the nature of the fault. For knock sensor and misfire codes it will apply maximum timing retardation.
Engine will run rough, with reduced power and fuel economy. I guess you could run it at high RPM's like that but it's probably not a good idea.

 

I had the knock sensor code. My engine ran very smooth through the RPM range. Plenty of power. Only symptom was it wouldn't shift into the highest gear, so RPMs were much higher. Fixed mine the next day.