By joshua vaden from Greensboro, NC
I rarely go to the trouble of browning meat before putting it in the crockpot to cook all day. I occasionally brown beef the night before if I'm making a roast, but never for a stew, pulled pork, BBQ ribs and, of course, I wouldn't brown chicken. I can't say I notice much difference in the meat's flavor or greasiness whether I brown it or not. It will cook though regardless. When I do brown a roast, the outside is "firmer" and remains more of a chunk of meat. If not browned, it tends to shred/fall apart more. Some recipes I have call for the meat to be browned, others do not. But like I said, I'm lazy so even when the recipe says to brown the meat, I often don't and it turns out fine.
You don't necessarily have to cook it. It will completely cook in the crock pot, but I highly recommend you brown it first.
I think it is according to the recipe. I like to get as much grease off of ground meat as possible so I usually will brown. But the others I think it will depend on what you are fixing in there.
Browning makes it more presentable, but IMNSHO, the whole purpose of crockpot/slow cooker cooking is to use the fewest pots and utensils possible. I think it tastes the same whether you brown the meat first, or not.