first to locate the leak is a procedure that he will follow and he will then tell you how it will be fixed. either by approved metal or there will be other option
i suggest just change what you have to that is the timing belt as of now and also check the baring if it needs changing. dont over think and if you tell your mechanic that you want to change other things then they may forcefully change other parts. let the mechanic see your car and see what he suggests.