Does anyone here have any information on whether the holes are pre-drilled? Thank you

Sorry, don't remember, but think there are at least a few. The wood is soft and easy to drill through. Sometimes the holes don't line up exactly, so maybe better not to. Just note that the frame is very light. So unless you're full of bottles, make sure it's not in a place where it can't accidentally pass.

Screws & spacer included. It’s a very very light frame, so not hard to assemble.