What material will you print out of?
I print with PETG
Are the red and clear inserts transparent?
yes, all the red, orange, and clear parts are printed with a translucent PETG so you can optionally add lights behind any of those parts to use as turn signals or illuminate the lights any way you want.
Mounting tab locations?
There are no mounting tabs, you'll have to bond tabs on where you choose for mounting.
Edit: the lights now have mounting tabs for ease of installation.
What glue is used to glue the prints together?
I don't glue the pieces together, it would be up to you to decide what adhesive to use and glue the peices together. Any 2 part epoxy designed for use with plastics works well though. Also I would recommend using plastic weld staples in addition to epoxy. It will hold things in place while the epoxy cures.