sorry to hear of it. is it 'bad luck' or did the previous owner conceal these problems! it's just a bummer for you.
what engine 155? this will determine what advice people give you about the engine performance.
the rear dampers are extremely easy to replace. even if you can't replace it yourself, any garage can do the job quickly. worth changing both sides, so that they perform the same. you have to decide whether you stick with something 'factory standard' or upgrade, to something like KONI or Bilstein or KYB, etc.
rising water temp could suggest a dying water pump, thermostat, or sensor.
ratty tacho could be a loose electrical connection (eg: there are little nuts at the back of the cluster that help secure parts and make electrical contact; these can loosen off over time, so are very easy to rectify), or faulty gauge.
loss of power could be an engine electrical (spark plugs, leads, coil packs, air flow meter, etc) or fueling (injector, fuel pressure, etc) or air induction (hole in piping, disconnection, clogged filter, etc) or some other problem!
steering wobble could worn front lower wishbone (bushings), worn steering/tie rods, worn dampers, bad wheel alignment, unbalanced wheels, etc.
so 'anything goes' in an old car. fortunately, they are pretty easy to work on, and parts are not difficult to acquire.
will you be fixing it yourself, or paying a garage/workshop? if paying a mechanic, we probably don't need to go into too much detail about how to do it.