DO I NEED TO PATCH CRACKS OR HOLES BEFORE SEALING?

Yes, large holes and cracks will get worse over time. Sealers are not intended to repair imperfections.

If you're considering Sealcoating your asphalt, repairing asphalt cracks and holes first would be your best choice, sealcoating is not designed to be an asphalt crack filler, it is made for sealing the surface and protecting it from the elements such as UV light, salts, oils, etc.