1) Yup, that's the engine BUT you also need the wiring, ECU, front down pipe with lambda sensor, immobiliser, immobiliser pickup from the ignition barrel and a key. Someone on the Punto forum sells a chip for the ECU that allows you to do away with the immobiliser and key. It is best if you can strip the car yourself so you get all the bits you need. It helps to have a look at a Haynes manual first.
2) do you mean the tin stone guards? These are supposed to protect the disc from stones thrown up by the wheels but IMHO they don't do a lot. Lots of cars run without them.
3) Try a specialist fastener supplier. Have a look in the Yellow pages for one in your local area.