RuiLing 2PCS Square Jack Output Plate Guitar Bass Jack Socket for Electric Guitar Parts and Accessories Black

What are the dimensions of the plate itself? Is it flat or curved like for the edge of a guitar. I want to use in a tight space to mount a 1/4" jack.

how is it?Does it work well?

What size hole is needed to use this?

How to know what speaker wire connects to which connector on the jack? positive /negative