On my commercial checkride, I got asked almost all 135 questions with duty times, SIC requirements, etc. My examiner was a commuter capt. So I sort of understood why he would ask those questions. I think he figured that as a commercial pilot you can fly for an airline or 135 op so you should know some regulations even though you'll end up as a CFI or fire spotter first. Many have disagreed with him asking those questions but IMO I would ask those questions too. You figure as a commercial pilot you can act as SIC for a 121 company so you should knowledgable about pertainanet regulations. Now the insurance companies would not even let you open the door of a king Air with the hours you'll have after your check ride but your given enough hours and time you could be a commercial pilot flying passengers. Find out what your examiner does besides being a DE. If he or she flies a CJ for a 135 Company than you may want to prepare for 135 questions, maybe. Good luck
Chris