On the subject of costs:
I had about 180 hours, inc. 20 or so ME hours (10 as PIC or thereabouts) as well as IR and it cost me in the region of $10,000 for both CPL's all in (exams, accomodation, aircraft, instructor, test fees, etc....). It cost me a bit more as I needed 250 hrs TT, though I saved a bit on the ME time.
You would need to do the IR flight test / exams, as well as ME CPL flight test / exams, though the flight test could be combined into one which would be more economic. Alternatively, and what I would do, if you plan on getting the SE CPL, I would do the IR flight test and SE CPL test in one hit, then the ME CPL and shoot two approaches to get IR privileges.
You would need a certain amount of dual time, a) because these are required by the FARs and b) you would need to be at the standard to pass the tests (there are some differences to JAA for all the tests).
cheers