You'll find all this pretty much by doing a search using the PPrune search engine, but in summary:
- You will not be able to work anywhere in Europe (under the JAA regulations) with your FAA licence unless you are flying an N reg aircraft.
- Your FAA CPL/ME/IR will need converting - if under 1500hrs TT = approved ground school (650hrs) 14 JAA written exams, CPL skills test and IR skills test (the IR requires a min. of 15hrs training to convert)
- If over 1500hrs TT you need to do whatever ground training is deemed necessary by the head ground instructor of a recognised FTU to write the exams. Skills tests still apply.
That's the bottom line. Hope it helps.