As indicated here, please post only 1 bug per topic:
Also, search for any existing report/request.
For issue 1, see existing report: Aircraft variant and livery setting is not saved between sessions. (it did in 2020)
For issue 2, see existing report: Aircraft Identification Configuration Always Resets
For the last request related to registration per aircraft, see existing wish: Save aircraft configuration (tail number) from flight to flight
Thank you !