You can get extremely edible results, which is good enough for me. The smoke-ring may be lacking from a competition grade result, but the flavour will be fine.
Presume you have a big-enough BBQ to have at least two burners. Only use the burner the meat is not on. If you have any prevailing wind and are not completely sheltered, make the hot side the upwind side.
Either get a smoke-box, or do what I used to and use foil. Soak 1/3 to 1/2 your wood chips in water to slow them down. Foil worked just fine for me, made a pouch, put in the chips and poked the up-flat-side with a knife to make smoke holes.
If you have a larger BBQ, consider adding in bricks or stones (no river stone!) to help maintain even heat. By having less air and more thermal mass, you will do better.
Let me meat come to room temperature before you put it on. Also no need to smoke right away, as the meat will not take it until it heats up further in the BBQ.
Happy Eating
Flash chilling is very simple. Just make sure you have a fairly large ice bath (ice and water that is at least 50% ice) and put the meat immediately from the heated bath into the ice bath. This will rapidly chill the meat prior to refrigeration. Make sure you leave the meat in the ice bath long enough for it to chill to the center if it's a thick cut or a roast.
1 How big should I expect the swings in my home fridge to be with normal usage?
The mild swings from opening and closing your refrigerator door a couple times a day aren't going to really make big difference. Just make sure you don't leave the door open for extended periods of time.
2 If I have a second fridge and the door rarely opens, what will the temperature swings be there?
There are a lot of things that influence the temperature of a refridgerator besides opening and closing the door. A refrigerator goes through cycles for chilling (and for defrosting) etc where the temperature varies. Some brands of refridgerators (i.e. Samsung) have separate cooling systems for the freezer and fridge portions so freezer defrost cycles do not cause swings in temperature in the fridge section.
Also, an empty refrigerator loses a lot more heat than a full refrigerator when the door is open. Storing plastic bottles of water or cans of soda and beer on empty shelves will actually make the temperature more constant over time since they retain more heat (or "cold") than air. Of course, if you turn a fridge into a beer-fridge, chances are that the door is gonna get opened a lot more.
3 Since the botulism concern is due to the vacuum, am I correct in thinking that this concern will disappear if I remove the meat from the vacuum to store it? Obviously, this approach would reintroduce all the normal safety concerns with storing cooked meat.
Sous-vide cooking should pasteurize the meat if it was cooked long enough and kill most . Keeping the pastuerized food that is sealed at a controlled temperature is going to preserve it for much longer than breaking open the seal and allowing any pathogens in before keeping it at the same temperature.
The most important thing is to follow the established safety charts for cooking times, temperatures, using correct flash chilling and then following the safety charts for storage temperatures and duration as well.
Best Answer
I am not aware of any rigorous tests done on a sequence like you propose. In the absence of data, I simply assume holding any open cooked product more than a week in the refrigerator is risky, smoke notwithstanding.
You can significantly boost your safety by soaking your brisket for at least 24 hours in an acidic salt bath -- perhaps with some brown sugar and aromatics for added flavor. Consider, for example, a recipe like Alton Brown's corned beef, which IMHO is tasty. (Add a dry rub of fresh-ground black pepper and, say, a little fresh-ground allspice and juniper, and you have pastrami.)
By the way, after smoking you don't have to wait for your brisket to cool: any vacuum bag suitable for immersion/sous-vide cooking can easily handle a brisket right off a 150*F smoker, no cooling/waiting needed. Besides, if you submerge the still-hot brisket after sealing in its bag into a 150-160*F water bath for 10 minutes, you will have effectively Pasteurized your product; with the residual salt and acid, I personally would be comfortable holding the sealed bag in the refrigerator up to two weeks (if I needed longer I would freeze it).