Check for the service history, look for cambelt changes (60k is preferrable to the alfa recommended 72k and it's better if the water pump is changed at the same time) etc. Uneven wear on your tyres is another common issue. Generally, they are great little cars and if well looked after, will give you no issues. Gadgets - depends on the age you are going for - lusso is a good spec with most the things you will need on board. There are some special models that were made towards the end such as the Q2, Ducatti Corse etc - which if you have the cash would be worth looking out for. Q2 is a limited slip differential that improves cornering no end.
Most models will have cruise control, but worth looking out for, also Look out for centre arm rest, leather seats, dual climate control, bose stereo and I pod adaptor to name but a few worthy extras. Good luck!