Yup, the Gel stain. I used foam brushes to apply both the stain and the top coat. I've got a Woodcraft store just minutes from me and they recommended either a cloth or foam brush. I never tried cloth application, but the foam brushes worked really well. I was going for a very dark finish over oak, so I never wiped it off as this stuff doesn't penetrate like liquid stains do. The Arm-R-Seal satin top coat I used was really incredible, the trick is never go back over the same area as it will self-level. With our family, this stuff is bomb proof...no scratches or marks after 3 years.
That's exactly how I made my terminal cups, but I made a rectangular hole instead. I made a 4"x3" hole jig from scrap wood. Attached the jig to the rear of the enclosure and ran a flush trim bit through a hole I drilled. I glued a piece bigger than the hole to the inside and drilled the holes for the posts.