I have a 1974 house with an attic that is about 5' tall in the center. It is currently insulated with about 6" unfaced fiberglass batts laid between the joists. This is rather skimpy, especially considering that I live in Fairbanks, AK where it gets down to -40 most winters. I am therefore looking at adding additional blow-in insulation (around R-33 was recommended) to the space. However, I have a couple of questions.
First, I know I need to keep the eve and gable vents unblocked. I am a little confused as to how to do this though. I have heard things like using cardboard over the vents, or perhaps putting some 1x furring strips up along the edge to keep the insulation back, but I don't know what would be best. The situation is somewhat complicated by the size of the attic - all the do-it-yourself sites I have found show wide open attics with steep roof slopes where you can easily get to the edges. In mine, however, this is not the case. It is, as I mentioned, only about 5' in the center, and rapidly narrows down as you get towards the edges, making it a VERY tight fit to get out to the eves. To make things harder, it isn't the wide-open attic that I have seen in the guides, but rather a truss type system, full of criss-crossed beams, making access even harder. Given this situation, what would be the easiest way of keeping the vents clear?
Secondly, I have been getting a lot of conflicting information about what the best type of insulation to use it. Some people are saying that blown-in fiberglass is better because it is non-flammable (I do have a wood stove chimney going through the space, so this is a consideration), and you don't have to worry as much about it getting wet. I have read a lot of people saying that you should never use cellulose. On the other hand, other people say that cellulose insulates better, and is cheaper, while being treated with fire-retardant chemicals that effectively nullify that advantage of fiberglass. So what's the truth of it? Which is the better option? Thanks.