Hard Tonneau Cover Install Question

Hello all,

I have a 22 Tundra Limited 6.5 ft bed TRD Offroad. I will be purchasing a hard tonneau, probably a Bak Flip or something in that line. I have a drop-in bed liner with no cutouts or pop-outs for a drain line.

Are there holes in the bed under the bed cover for this? If so is there a diagram of where they are?

The drain line will go in the front wall of the bed, Is that fiberglass or aluminum? If fiberglass what type of hole saw or bit should I use if I drill it?

Thanks for any assistance.