How to convert an EASA CPL(H) to FAA CPL Rotorcraft With a Helicopter Class Rating? I just finished my CPL(H) license and was just wondering if it is difficult to convert your license to an FAA (or TCCA) license. 

Do you have to do additional exams or check rides?

It's hard to find a step by step guide to do this, or do you recommend to contact a training organization in the US or Canada to perform the conversion?
I just saw somebody try to do this. They had an EASA CPL(H) and a FAA PPL(H). The DPE needed to have a letter, sent from EASA to the FAA in Omaha, Verified, and then a copy sent to the pilot. This letter is EASA confirming the logbook entries attained in Europe were legitimate. This letter is only valid for six months. Despite getting the necessary flight training from a FAA certified CFI, as per the appropriate requirements, without this letter a DPE can’t administer a practical exam. 

You need to pass the FAA practical to get any FAA certificate. Written test requirements vary.