Regarding JJ being alive or not when MG and DW saw AxC carry him in, I just keep thinking that carrying a dead body in front of two people not involved in the whole thing seems like something even this merry band of idiots wouldn't do. What if the head/neck or one of the limbs ended up flopping out of the "cozy sleepy" position in Alex's arms? I just don't think they had enough up close and personal experience with dead bodies to be comfortable parading one in front of people to pass it off as alive.
I would believe that JJ was sedated in his uncle's arms.
When I heard about all the duct tape and how the body was positioned with the duct tape, it made me think this was some sort of ceremonial thing. If Joe Ryan was cremated, and one of those documents CD provided LV on the darkness levels of people around her referenced JR as "sealed away," or something similar, here's my thought. If Tylee and JJ were both "zombies," they tried to cremate Tylee's body to also "seal it away." But upon seeing how much time it took and how difficult it was to burn a body completely, they couldn't do the same with JJ--not with Tammy sleeping in the house or soon to return from work. So perhaps the duct tape was used to create something almost like the wrappings of a mummy, to "seal" him away as well.
But then I was watching Court TV tonight and they had on someone from FSU who was a certified crime scene investigator, and he suggested that the elaborate taping was done to "contract" the body, to make it fit into a tight space and to better ensure it didn't move much later as it decomposed, so the ground above it wouldn't cave in. This makes sense to me. Also, I thought that having the body basically all taped together like that would make it more difficult for an animal to dig up the body and make off with singular bones. They wanted that body to go underground and stay there in one piece. JMO