Peppers: You can control the heat with the type of peppers you use. Between the marinade and the cooking, a lot of the heat will be lost, so dont be afraid to throw a couple of whatever hot peppers you have on hand. I use 2 large cayennes, 2-4 chilies, and a token jalapeno.
The preperation: combine everything except the bay leafs and the meat in a large zip lock bag. Add meat and thouroughly mix. Let marinate in the fridge at least 2 hours preferably until the next day. Fire up the bbq. Remove meat fromthe bag wiuth as much as the marinade as possible still clinging to it. Place half of the bay leafs on the meat. Dump the remaining marinade or use it as insect repellant. Cook very slowly over medium heat turning often. If your grill has a vented hood close it . Do not let meat burn. Cover and cook about 1/2 hour. After 1/2 hour remove the bay leaf, turn meat, place the remaining bay leaves on the meat and cook till done (About 1/2-3/4 hours more depending on the heat). Eat. Break out the beer. You'll need it.