[The Builder]

It may be pretty hard to get between the back of the studs and the brick. You can try to pre do, if I may say, the Tyvec. What I mean is, you can apply the Tyvec to the board before you try to attach it. Also try slip some adhesive on the edges of the tyvec, if perchance it will adhere to the older surrounding Tyvec that will remain.Also cut the Tyvec wider than the board. I can't see the problem at hand, so I can't really judge how much room you have to work with, but it sounds pretty tight. As far as the insulation replace the ones that got wet. And replace the sheetrock