I would do some googling and start out simple. Controlling your temp is key and more difficult with a charcoal. I've only done one brisket I have an electric smoker so it's pretty much spice, set temp, and add wood chips. Methods will vary from source to source on the web so I try to find the average of what people do.
From what I remember about doing a brisket:
Rub (Your choice, there are infinite recipes for this so pick what sounds good to you. I prefer one with a lot of black pepper.)
Temp (225-250*F from what I remember. Low and slow is the key BUT you need to get the meat from 40*F - 140*F in under 4 hours or you can allow resistant bacteria to grow making you sick. This is prob the single most important thing when cooking anything You may find that you need to give it more heat up front to get it out of that range in time and then taper the heat back once you get past it.)
I used an injector to inject beef broth into my brisket. This is optional, but will keep it from drying out.
I used an apple and hickory blend for the wood. Hickory is a very strong distinct flavor, but I do like a stronger overall smoke so the apple gives me a sweeter generally smoky flavor and the hickory gave it that extra kick of flavor without overpowering it. 5-10:1 is about what I use. It's just an eyeball, I don't actually measure it.
Once it hits 160-165*F, pull it out and wrap it in foil. You may experience a stall in the temp of the meat at this point so don't worry if it takes a while to get past this temp. The fats are starting to break down so it takes extra time to get past it.
Let it finish to 190-200*F
That should at least be enough to make you dangerous from my limited memory. I know everyone loved the one I made.
If you have leftovers, reheat it as a chunk covered in foil in the oven. Inject beef broth into it. 300*F. Save the juice in the pan if you have more leftovers and inject that into it (more flavor).
Also, the thicker end will be more fatty. I saved that and trimmed it up and made delicious beef vegetable soup with it. Use the thinner end for your traditional brisket meal.
If you want to do the chicken legs at the same time, make sure that the recipes are going to mesh well. Temps, woods, etc. Don't forget the legs are going to take a lot less time than a full brisket so don't put them on at the same time.