Presumably rust isn't a problem in Malta therefore your new purchase should live forever with good routine servicing. Petrol is the sensible choice for short blasts. The Ts is a great engine. On a test drive:
Don't worry about any knocks and creaks from the front as all 147 will need wishbones and drop links reasonably frequently. Ask the seller to drop the price accordingly. The roll bar bushes however are expensive to fit and this is felt as knocking through the floor. The subframe needs removing so a seemly minor fault can cost 4hours of labour to rectify. I'd imagine air con is essential so check it's icey cold as it's expensive and time consuming looking for small leaks. Don't believe the seller if they say it just needs a regass. Clutches are costly (like any car) but the petrol cars fair better. At this mileage all should be good. The pedal should be light. Again this is not an Alfa issue but a recent timing belt service adds value to the car and plugs are reasonably expensive. If it needs a big service then your first year of ownership could be costly.
Generally in my experience Alfa ownership is no more costly or daunting than other marques. Welcome to the gang.