No idea if someone cut the slits, they were that way when I got them.
Yes, the small holes are all for post lamps. The wiring and sockets are in place, and I have the lights I can throw in.
Your instrument panel has 1/4” holes that take a rubber grommet. The plastic overlay has pegs in the back that slide into those grommets. Friction fit.
Shipping is included in my price.