Highly recommend you go to www.deejayssmokepit.net. DeeJayDebi has generously made an electonic book for all. You will find a fantastic poultry rub, brines, recipes and many other ideas. Just a ton of information. Also, go to the forum "General Discussion", 2nd sticky. I think thats the site along with a cooking chart with times and temps for various foods. Good luck!
I smoked a couple a while back. I put plain ole salt and pepper on them, but I recommend buying Jeff's Famous Rub and using that though.
My biggest bit of advice on turkey legs is brine. Brine them for several hours if you can. Search around the site and you will find tons of brines for poultry. If nothing else put kosher salt and sugar in a bunch of water and start from there.
I cooked mine to 165. The skin was tough as leather. And that was with apple juice sprayed on them every 30 minutes. The meat was very juicy though.