So you've got your right hand on the cyclic (if that's what its called), left on the collective, feet on the pedals at all times.
Yup!
Radio frequencies, QNH and transponder are all set on the ground before lift. Once flying straight and level at a couple of thousand feet, changing these is not too much of a problem; put the friction on the collective and quickly twiddle the knobs!! It's easier flying from RHS but I used to fly a helicopter from the left hand seat in which case I had a choice. I could try to hold the cyclic with my knees and twiddle the knobs or, put the friction on the collective, hold the cyclic in my left hand and twiddle the knobs. Neither of which resulted in elegant flying!
I don't tend to write down ATC clearances; I memorise them. Most controllers are aware of a helicopter's limitations in that respect and tend to give us information, one bit at a time.
Cheers
Whirls