Q&A for How to Use a Biscuit Joiner

Yes. You will want to align/center the cutter to the thickness of the wood you are using. The adjustment is at the side of the fence. Check during your progress to make sure the setting hasn't changed.

Full-strength Clorox will easily take mold out. Pour directly onto the stain, then do a light wash to clear the drum (without any clothes in the machine).

This depends on lots of things if clamps don't work for whatever reason, you have to get aggressive and in whatever ways are necessary Like take two other boards for top and bottom, and use screws or bolts to tighten with wrenches exerting more force that clamps or it's holes don't matter. Screw the screws into the project.

As long as the plywood is in decent condition, there is no reason a biscuit joiner couldn't be used. Make sure to use glue.