Here is a good article on Smoking Fish
that explains the processes (brines, temps, time) for hot and cold smoking fish.
The problem with cold smoking is that you really can't do it in the summertime because the ambient temperature is too high (the air is already as hot or hotter than the max temp you want for the smoke).
Although the hot smoking method in the above article starts out at 90ºF for a couple of hours - you don't have to start that low. Here is Alton Brown's Smoked Salmon
method (maintains 150ºF throughout the smoking process) - which is close to what I've done (I usually started out around 120ºF).
As for a smoker - all you need is a way to generate smoke, contain it, and control the temperature. To see how simple your setup can be ... look at Alton Brown's Custom Corrugated Vapor Colloid Applicator
(cardboard box smoker).