It really depends on what type of coating you plan on putting down. If you are going to use a true epoxy coating then I would use a 2 part epoxy resin mixed with a silica sand to repair the cracks. If the pitted areas are prepared properly you could use the 2 part epoxy with silica sand as well...
The paint store or even Home Depot sells a product called Willbond. Put some on a rag and wipe the area you want to paint. It stops paint from "crawling"
Acid etching is not the answer. Shot Blasting is usually the best way to prep the floor but usually the most expensive too. Gringing the floor is an option but try to rent a gringer that uses a diamond bit and hooks up to a vacuum system. Boshe makes a nice set up that I have used for years to...
I work with urethane foams daily and have not found a product that will remove foam once it has dried. Usually takes couple layers of skin with it if you try to peel it off.
A dehumidifier will definetly work but it has some issues. Some one already mentioned the heat it generates for one thing. Second the cost to run a unit is costly per month and worst it isn't maint free. The multi-vent is a maintenance free unit installed in the garage that by means of air...