IDK if this helps, but when I did pull-outs I used rectangles of ripstop that I had already hemmed around (for looks). After I measured on one side and made my mark, I pinned the rectangle to that side and taped it down with scotch tape. Then I went to the other side, pushed the opposing rectangle down the pins, and scotch-taped it in place. Remove the pins and you are ready to sew both reinforcers on at the same time. Worked great for me.
Definitely seam seal. There is a great thread on here about homemade seam sealer made with mineral spirits and pure silicone. I made some and it worked great.