-Turn Qual just means that I can start the APU/Engines to be able to run BITs or test systems that can't be tested on ground power.
-It's possible only if you have ground power connected. You can't have them on with just battery power.
-For ATIS, I'm not a pilot, but I'd assume they'd get that during their briefings and also after startup when radios are online for an updated ATIS.
-I can't speak on the last question because I have never really dealt with civil aviation.
I hope I was able to answer some questions!