Renault scenis Year 2000 Ignition lock defective

Hello your motor talker , last week failed the return spring of my ignition lock Scenic Bj.: 5/ 2000 1,6 ( starter in the ass sorry defective ). Starter has been changed with much effort (reinforce thru axle ). But my ignition lock is def. , does not jump back from the starter creation . Question number 1 : Can I install a used ignition lock ? Question number 2 : Must be changed with my model the engine control unit ,or is it enough if I have a born lock with d in order to buy keys ? (because of the coding) Question number 3 : Can I encode a replacement lock on my model myself ? Question number 4 : What does a new lock at Renault cost and can I then keep my old key ? thank you for your answers !!!