5/8 in. x 5-1/2 in. x 94-1/2 in. Polyurethane Aberdeen Baseboard Moulding

You can use a miter saw with this moulding.

You could, the finish is a flat white, well covered, the ends are not white when cut if they are going to be exposed you'll need paint

these are flexible, I installed on an arched wall

If glued use an adhesive.that is compatible with the trim you are using. Check the tube before buying.. nailing is the best way because it allows you to draw the trim tight to the wall that is not perfectly straight. Glue eventually looses it’s grip or oozes out if you apply to much

Every material expands and contracts. Never put dissimilar materials together. Polymers have a greater coaficient of expansion than wood. However wood is more sensitive to damp or dry conditions. Bottom lin is where you use it. This is why you often see a gap between crown and the ceiling. Homes dry out in the winter and swell in the summer. Polymers react to direct sun but are pretty stable in conditioned space

Up to 20' some stores

Instructions suggest using a bonding agent, I used 1 1/2 inch to tack it into place while the glue set, enough to pass through the baseboard and drywall into the studs

Yes it can and you can use screws to attach it however be careful not to over tighten so the screws do not pull through. Another option is using finishing nail with an air gun and adjust the pressure so it does not shoot through as well. I would recommend painting these as the weather will have an effect on the exposed side of the molding. Painting will protect it and help keep it for years to come.

This depends on how particular you are. You may have to shave or shape the joint between the two pieces I don’t think the two are exactly the same thickness so you may have to caulk behind the joint so there is no gap.

No, this can't be used inside the shower.