The duration and wood type is a matter of personal preference. The flavour of smoking wood, together with the length of time you smoke your food for, the stronger the Smoky flavour.
Cold Smoking times vary enormously from as little as 2 hours more than 72 hours.
Once you have you smoked your food for the desired amount of time (and not intending to eat it straight away), it is a good idea to rest it to allow the smoke compounds to permeate the flesh and balance the flavour. 24 hours in the fridge should be sufficient depending on the thickness of the meat. With cold smoked products this can also allow the curing process time to continue.