Cynic78, you won't be credited with any theoretical knowledge requirements until you have achieved the requirements of Qq1-2 above. Unless, that is, you have a PPL with FRTOL - you would then at least be credited with any RT requirements.....
Once you have met the 2000/1500(500) requirements, you will then need to complete a Fixed Wing Bridging Package, followed by passing 4 ATPL(A) exams (Air Law, Mass&Balance, Performance, Operational Procedures). You would be credited the RT theory exam and practical test and, if you have at least 500 hours as a pilot on multi-pilot aeroplanes, would also be credited with the Multi-crew Co-operation Course. If you are still in current flying practice when you pass your exams, you should be exempt the CPL Skill Test, but would be advised to fly a civil IR on the King Air - you would then be able to open a CPL(A) with a Single Pilot IR and Type Rating for the BE200 series and would hold ATPL(A) knowedge.
The CPL(A) / IR + MCC and ATPL(A) knowledge is colloquially referred to as the 'frozen' ATPL.