No requirements whatsoever apart from the PIC ensuring that a qualified person is strapped into a command seat and the usual requirement that the PIC ensure that the operation is safe.
I reckon it takes about 30 seconds to get used to the RHS in a light piston single or twin.
From memory (has been a while since I had one in front of me) but doesn't the AOM for the C172 have a requirement that the pilot be seated in the LHS? The aircraft is designed to be flown from the left.
I wouldn't think so. Consider the C172 on a TIF. The pilot is in the RHS, the first time student is in the LHS.
Ref CARs 176, 224 (Operator must designate 1 PIC), 243 and 225.
FRQ CB