Oxalic acid is often used to remove rust. It's available as a white powder. If that doesn't work you could use something stronger like Muriatic acid...
Our door manufacturer used Freeborn cope and stick for all the passage doors 1-3/4 Poplar w/mdf or Cherry and they've been good for 20 yrs. The entry...
Tesla conveniently uses a $10 passive RFID card or the Bluetooth built in to your phone. $400 key fobs seem a little outrageous given the technology...