Good questions, especially the one about wave makers.
Being a noob here I would hope that some one will correct me if I am wrong!
The overflow is siliconed to the glass. Attaching to the plastic trim is just asking for a future leak to happen. External overflows usually collect from drilled holes or a cutout. Internal overflows are sized and siliconed to the interior of tank.
Herbie setup is what I have planned for.
Cheers!
T