oh, gosh!
No, you dont HAVE to brumate to breed. I suggest doing it, and practice it personally. I don't want to get in that debate, though. Plenty of old threads on the topic, for that matter the CSM covers it, to my recollection. If you live in too hot of a climate to do so, you will still breed colubrid snakes.
As for the temp change, I am far from scientific about it. Stop feeding, move them into brumation room, cut off heat to room, it gradually cools. I keep a good digital thermometer on top of the cages to keep an eye on things. Open a window on evenings of warmer days if the room temp creeps into the lower 70s to cool things off. It's the kind of thing that gets you up in the middle of the night the first time you do it, but you have to remind yourself to check on them after a few years! They are pretty tough creatures if in good shape when going down for the nap.