Building a banquette. The frame was easy with 2x4s. I'm using 3/4 ply for the lid and hinge strip trim out. Planning on using a surface flush piano hinge but am uncertain on the best way to install it. The frame is already fastened to wall but have not fastened the trim out or lid. Should i assemble the hinge on them first, then nail and glue down the hinge trimout? I'm open to other hinges.

Also, is there any issues with water based primer and paint on thin veneered plywood? Hopefully I'll be okay with thin coats.

Thanks