regarding the brine, use whatever beer you would like. I like dark beer so a dos equis or similar would be fine(shiner bock)
shock top makes an apple beer that would be perfgect for the cold smoke you are planning, so that too might be worth your consideration.
THE IMPORTANT PART IS TECHNIQUE!!
dropping the birds in to a hot marinade and then icing them quickly after, helps to draw the marinade in to the meat of the bird.
it's thermal- dynamics !
you can always just drop them in a cold marinade mixture and let them rest and marinade foir 4 hours, my method just reduces the time and SPACE required to refridgerate all your birds for 4 hours.
good luck, enjoy !