Hybrid battery basics on 2002 Prius....

I bought a 2002 Prius, and after about 3 months the red triangle. Took apart the hybrid and found green/blue corrosion on all the terminals. Cleaned them to shine, add dielectric grease and fine for 2 months. Now I have a what looks like a high temp in the dash. When that light comes on the car won't move until I shut it off and then back on and good to go for the 3 miles to home. Not willing to drive any more until I did some research. I stumbled onto this site, and wow, what a resource. Too much to wade through, so I thought I could get some pro advice because I'm a little weak on the nomenclature. Car has 220,000 miles, and I ordered a BAFX pro code reader.

Just for my basic knowledge after pawing thru this forum, here are some questions:
So what are voltages on each cell of the HV battery suppose to be when car is off? Mine are 7.2V to 7.9V
How do you determine if a module/cell is bad?
What is balancing the modules/cells?
How do you see the inverter pump working?
How long should I be able drive before the ICE comes on?
Can a high temp light be triggered by the inverter working to hard? Maybe my hybrid battery is too weak?

I appreciate you letting me into your community, and I look forward to learning from you.

Thanks in advance from a newby.