I have a cement slab that had a plastic film and then pergo flooring. Removing this floor. Right now, I just want to seal cement and epoxy paint once I get all pergo removed. First, since I am only sealing do I need to degrease and etch the cement? Second, can I epoxy paint over the sealed cement?
Degrease and etch will help paint adhesion. the epoxy paint may be enough to seal the cement by itself, check the preparation instructions on the finish coat you have chosen.
Diamond grinding is also something that is common for concrete floors these days. I epoxy painted my garage floor and for preparation I had the floor ground with a diamond grinding machine. It looks like a floor buffer, but rather than a polishing pad it has a disk with metal fins that are impregnated with diamonds.
This basically sands off the top thin layer of concrete and preps it for paint or other top coats. The floor must be cleaned very well afterwards to remove dust, but no etching is needed since the surface of the concrete is already open.
Whichever route you take, for a long lasting epoxy or painted concrete surface, the preparation is the most important step. Even a basic epoxy paint will last years with proper prep.