paint first, so as to not mess up the nice new floor. Make sure the floor is dry, not weeping and ready for prep.
Flooring should meet your needs, tile porcelin or ceramic, grout or not and so on. If you are welding the epoxy might be best or perhaps coating that can easily be "patched" or restored. To keep dust down, just a sealer - but most of them will dissolve or get stickey with fuels or chemicals.
Biggie is DIY or pros? I would start with calls to the several folks on this forum that do this for a living and have done hundreds of floors. If you go DIY prep is the magic, don't skip or mix manufacturers, unless explicitly told to.
Good luck, and enjoy