Definitely new belts before you even start it....
Things to check on '93 SSs. Frames can crack on the top tubes near the headstock. If it has an alloy swingarm then check for cracks at the pinchbolts at the engine end. Leaking clutch slave cylinders (not difficult to sort). Check for broken cylinder head bolts. Clutch noise is normal and doesn't really go away even with new basket and plates. Petrol tanks can rust internally especially on the back seam. Engine will sound noisy "They all do that, Sir"
If it's been sitting for a couple of years the fuel system'll need stripping down and cleaning out plus all the other usual service type stuff.
On the other hand if that all sounds like a lot of work SS's are a pice of piddle to work on. All the guff you read about desmo valves being tricky is rubbish. Compared to working on and adjusting the valves on a modern UJM you can reach everything with hands the size of Guy the Gorilla. Trickiest thing about doing a SS's valves is working out how to support the backend when you take the shock off.
Good info sites include
http://www.ducatitech.com/ and
http://www.ducatisuite.com/home.html Darren