@Mark Boyce Mark when you are ready for the batting, take a cheapie 2 or 3 inch paint brush, pour on the glue (buy a gallon) and spread it around on every contact surface. This coat should be relatively thick - not thin like a paint coat. Take the precut batting and apply it to the glue pressing down (light to medium pressure) to get a good bond. You can use a different stiff brush to push it into "cracks". It will take a day to dry. Then trim the edges as needed. I usually use craft scissors. Prepping the substrate is the real work as you have to decide what kind of surface structure you want.
Precut batting - take the batting and lay it on the surface press it into the substrate, and mark the outside perimeter, then cut to shape. Sometimes you will need to cut the batting to eliminate bunching or thick folds in areas. Reset it in place and make any final needed cuts. I usually leave an inch or so overlap. Its easier to trim if you have something to hold on to while cutting. If this is an in-place application, just cut to size. I have not had great success at hiding seams so I try to minimize them or apply the batting joints into inside corners to make them "invisible". Otherwise they have to be covered with landscaping.
Regarding the glue - you want to apply the glue as fast as possible to prevent skinning. I can do 6 to 8 square feet pretty quickly. Picking up the glue onto the brush is too slow for me, so I pour a puddle and spread, etcetera - etcetera - etcetera (think of the voice of Yul Brenner - King and I).
Regarding painting - this is a load the brush and dab, pushing the paint into the batting. I always have to go back the next day and reapply to areas that did not take the paint well.
BTW if you have been that busy outside - you must have had a great surgeon. Glad to hear it is going well long term. Jeff
Watching Chris' videos and reading your description, I do need to get a can of brown paint for coloring the batting once set.
