Insulation + air-sealing plan for a poorly vented attic – GreenBuildingAdvisor

I’m considering blowing-in cellulose insulation in the attic of our 125yr old stone house in southeastern PA, which currently has zero insulation. 

The attic is divided into two halfs (original home and addition) by a 24″ X 36″ access hatch. The old half has a total of 3 gable end windows and the addition side has a ridge vent. There is no other venting in the attic, but I can see some daylight at the eaves in spots. There is nothing in the attic except for  ductwork (bath fans and dryer vent) that terminates outside.

My plan is to air seal as best as possible, but the attic is entirely covered by T&G floorboards. I’ve opened up the floor above all of the 2nd floor light fixtures, bath fans, and drop-ceilings for closets & stairs, and against the chimney. I plan to air seal those spots as best I can, along with the access hatch. I’m sure that still leaves plenty of trouble spots that I’m not uncovering where air leaks are happening. 

My questions are: 

– Does a less-than-perfect air-sealing job and then blown-in cellulose add any risk of mold / moisture in the attic? The poorly vented attic & roof has survived 125yrs…am I potentially introducing any problems with this plan? 

– Once I blow in cellulose it will be harder to access the windows on the gable end….should I leave those open permanently for venting? 

– Is there any point of adding insulation baffles, even though I don’t have soffit vents? 

– The insulation contractor I’m talking to wants to pull up more floorboards randomly throughout the attic to allow any moisture to escape into the attic. Insulation would be blown beneath + above the attic floorboards to achieve R-49 (14.3″ total). Does this make sense?

Thanks for your help!