I didn't answer your technique question much either. But it's not hard to figure out. The best part of sous vide is being able to season/marinate your food and cook it in the seasoning. The purpose of the immersion circulator (the actual device that controls the cooking) is to precisely control the temperature of the water bath and circulate the water around for an even and controlled cook. Most devices can get down as low as 110° and as high as 200°. There's a timer setting so you can control how long it runs.
Cooking via sous vide (French for "under vacuum") lets you get around food safety concerns because of the duration of your cook. For example, pork is considered safe above 165°. But since most pork is a dry mess even at 150°, it's hard to get edible pork that's not cooked to oblivion....even more so with chicken. So with sous vide, you cook at a lower temperature for a longer length of time.....sort of like a pasteurization process. So cooking chicken to 145° for 4 hours will get you a moist and flavorful piece of meat, but also food safe below typical USDA recommended temperatures.
But, there is give and take. If you cook chicken for 24 hours, it's going to be a mushy mess. Most sous vide devices will have instructions and guidelines for you to use. A backstrap at 4 hours is plenty, but a medium rare chuck roast will need 12+ hours. For me, I set a backstrap at 122° and run it about 2-4 hours, depending on my timeframe. When it's done, I don't want it going higher than 130°, otherwise it'll be too overdone for me.
But the finished product isn't one you pull out of the plastic bag. It's cooked, but usually a pretty pale and pallid consistency. The key to finishing a sous vide piece of meat is the final sear. Doesn't matter how, but a high-heat blast will get the caramelization needed for a nicely cooked meat. Slap on the grill for a couple minutes, sear in a skillet with butter, or as chaneylake does with filets, a butane torch. When you're done, the meat is consistently cooked through, with an outside sear zone. Here's an example of two pieces of meat cooked traditionally vs. sous vide. To get the center of a piece of meat to be the right temperature, you have to cook it for a while on heat, which will transition from over-done down to the right done. Sous vide eliminates that and gives you a finished product that's more uniformly cooked to your desired level
