rob,
The only operators I'm aware of that will hire you straight after your CPL are the North Sea Operators - though they have a lot of guys on their books right now so don't count it.
You can count up to 100hrs of your helicopter P1 time towards the 150hr requirement of a CPL(A). I suspect it's less the other way around but don't know. Theory exams wise, it's 3 extra to go from ATPL(H) to ATPL(A) and 1 in the other direction. That will change when they eventually create the bridging exams.
Most people probably instruct after the CPL(H). You need 300h before you can do the JAA FI course - pay is then around 40-50 gbp per hour from what I've seen.
You can become an FAA instructor (with a 2 year J1 visa) with about 150 hrs but most U.S. schools don't hire with less than 200hrs. Pay is around 15-35 usd per hour. In the busy schools you can get 700hrs or more a year.
Costs wise - about $50k USD full time - check out OATS and Helicopter Adventures
Hope that helps