It's very possible for plant/tree pollen to get on a MJ plant. There is so much pollen at my house in the spring time from the trees that it turns the driveway yellow. Maybe try vaporizing or smoke it from a bong if your worried about the pollen as those will filter more of it out than a joint would.

Sounds to me like the harshness, and the fact that it chars but doesn't burn are related. It probably isn't dry enough to smoke. Dry it out a little more before your next smoke and see what happens.

EDIT: I was just thinking it would be cool if the cedar tree cross pollenated the mj plant and grew a 40 foot tall cedarijuana plant. Like how the Simpsons made the "Tomacco" plant from tabacco and tomatoes.