In some of the smaller aircraft such as the H300, R22 & R44, have a look at how wide the cabin is and where the "main" fuel tank is located.
This may sometimes dictate in which position the P1 is seated as this will have an effect on lateral C of G.
As far as the LH or RH seat is concerned while changing radios, think of the left handed pilot who has to fly right hand on the cyclic all the time and not only all you RH handed pilots.
As far as the collective is concerned, you could always use the mark 1 collective friction (ie your knee). Pilots have been using this device for eons!
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