first off where are you based?
the click clack is a common fault, will cause no problem is just annoying, if its the same thing. mind blank on the name of then.
the whirring noise i can't help with i'm afraid.
does the rear wiper not work or is it just the washer jet. i have a spare motor for the wiper if you want it. will do it nice and cheap for you too.
your mechanic might be right though, sell it and get a newer one