Insulation, Radiant and Vapor Barriers - blowing in cellulose

My attic crawl space is about 1200 square feet. I went to home depot and they sell bags of cellulose for $3 a bag. I figured that I needed 30 bags which would add r-13 to my ceiling. I have batts and some loose fill fiberglass. Home depot gives you the blower machine for free. SO it seems that i could pull off the job for $100. The question is how easy is it to use one of these machines? I assume that this is two person job- One to fill and one to "squirt".

We did have some ice dams but no water leaks.

A related question. If the cellulose get wet and needs to be removed should I line my current layer of insulation with tyvek( i believe that tyvek is not a vapor barrier). Would this make any removal easier or if we have not had a leak in 20 years hope for the best.

Thanks

First question is how thick is your current insulation? Next question, what in the minimum "R" value required for an attic where you live? Next, what do you have in mind to prevent you blocking off the soffit vents when you blow this? Also, why stop at 4"? I wouldn't put in less than 12"!! And I think you'll find it's a much easier job with 3 people -- one loading the blower, one blowing, and one at the access hole to help with the hose, lite cord, and communication. Forget the Tyvek.

Lefty is correct.