#8 pan head screw is recommended. Depending on the wall type, there are different kinds of #8 pen head screws. For commercial models, #8 or #10 is recommended.

Double-sided tape and glue cannot be used on sheetrock and plaster walls. Special mounting screws for soft walls are necessary and can be purchased at any hardware store.

Yes, although fiberglass is not an ideal surface. Ensure both pieces of adhesive tape have solid contact with the fiberglass and that the glue is not covering the adhesive tape. Press down firmly to allow strong contact.

Pry off the unit and clean any remaining residue with any mineral spirit.

Remove (scrape or wipe) the silicone glue, then scrub down the area with isopropyl alcohol (IPA), or mineral spirit to remove any remaining residue.