I am in the process of renovating my house and have come to insulating my attic, which will be a finished loft (bedroom). I have 2X6 rafters that run approx. 15 ft from soffit to peak. What R-value would you recommend and do I need rafter/soffit vents to run the whole length of the rafter for ventilation? Keep in mind I live in Upstate NY, also I do not have a ridge vent. Thanks for the advice.