Even if you had a foreign IR, you still have to do the full 55 hour IR course.
Doing the CPL course (25 hrs) gives a 5 hour reduction, making the IR a 50 hour course.
The IMC may be an unnecessary expense, so I didn't do one. However, there's always the safety aspect and of course it's good practice for the IR training which is extremely expensive if you overrun on hours.
Luckily, passed mine first time, but many didn't.
Good luck, whether you do it or not.
Personally, I would do the IMC rating, then hours build in The States where you'll get free approaches and lots of practice before the IR.