I would make sure everything got air sealed before adding more insulation.
Just rip some 3/4 OSB for walk boards.
I duct tape a piece of 3" PVC to the hose so I can hit all the outsides while standing in the middle.
Make sure to add plastic or foam baffles in the rafter bays near the soffits so they do not get blocked up.
Where is this sheetrock your talking about? On the attic ceiling?
Got any pictures?