I use a micro fiber cloth to remove finger prints on the black baffle and expect any good paste wax will be good fro the wood sides and back.
I had a tweeter cap fall off and ordered speaker glue from Simply Speakers. It cost $10 and I probably used 17 cents worth. It is white, rubber based, and will flex. I suspect Elmers rubber cement at a third of the cost for 4 times as much would work just as well, although the thin spigot on the Simply Speakers bottle was a way to not over apply.