Does the cabinet handles come with long screws?

Yes. Matched with 1 inch and 1-3/4 inch screws, the handles will be suitable for almost all kinds of cabinet and drawers.

Will the hollow handles bend or warp if pulling a drawer that is a little heavy?

No. They are very sturdy.

How big do I need to drill the holes for the screws?

The diameter of the screw nut is around 1/4 inch. Please drill holes smaller than that.

Is the black finish a flat black or shiny black?

Matte black.

Is the finish painted on the cabinet handles?

The finish is powder coated and is very durable.