#1 if motor is fine then check the wiring and check the switches, need to take the door apart and test everything with a multimeter.
#2 same as above multimeter time
#3 some cheap system eat a key, others have a module you program but need 2 keys either way.
#4 ignore it, check your tires semi regularly and don't worry so much. Or pull all the needed parts from a wrecked lancer, but typically the TPMS system what fails isn't the whole system just the sensors in the tires.
Audio: JVC KD-ABT22 / JL sub+speakers / Sound deadening
Engine: WR-SRI / RRM 25% UDP / 6G75 TB
Other: RA Mudflaps