I would get the rust sorted but it sounds about right to me i payed £ 4.500 for mine a few years back and its a 58 reg 64.000 miles
so price seem about right. As for noses if its coming from the passenger side most will be the relays clicking in the fuse box mine dose it all the time.
i have a click that come from the clutch pedal and i no its a switch bugged me at first but you get used to it
i would ask the place where you bought it from to sort the rust out
i love mine as its been a good motor touch wood.
twanging sound when I pull away after having applied the brakes. sounds like sticking hand brake cables