A: The Everbilt 5/16 in.-18 tpi Solid Brass Wood Insert Nut pilot hole would be 3/8".
A: For the #10 Wood Insert Nut a 1/8” size predrill is recommended.
A: I had success with a 9/32 inch through hole with a .03 chamfer on the front face and a chamfer on the back face to the full 5/16 diameter on the back face to prevent breakout. This was in 1/2 inch five ply birch.
A: The notched / slotted portion should be installed up or facing outwards.
A: The notched portion can be used to screw the insert into the wood. This would be on the outside.
A: This wood insert accommodates 5/16 in.-18 tpi screws.