If the water on the stains does not bead, you are good to go after the etching. I have done 3 garages using UCoatIt and I had stains in 2 of them and they turned out fine after the degreasing and etching. The medium gray should hide minor stains. I strongly recommend using the "AF" version of UCoatIt.
Most importantly, though, is to make sure you don't have any moisture wicking, and no sealer on the concrete. To find if you have a water problem, place a piece of plastic on the floor and tape it down. Remove it after 24 hours +/- to see if the floor under it is wet. If it is, you will waste your money coating the floor. And if you have a sealer on the floor, you will need to grind it enough to get a mechanical bond.
If you are using their "Fleks", you should get enough traction to eliminate the need for the non-skid material they send with each kit. If you still want to use the non-skid material, use it sparingly or the floor will be very difficult to sweep. I found that the best way to apply the Fleks is to throw them as high into the air as you can and just let them fall into the final color coat, then apply the clear over them after the color coat is dry.
UCoatIT's pot life is not very long so it would be best if you had someone working ahead of you doing the detailing. Also, watch the temperatures if you are in a cool climate area. It is best not to try to apply it if you expect it to get below 58 to 60 degrees while drying.
One final suggestion....apply the base coat like they tell you to but apply the color coat and the clear coat heavier than they recommend. Don't roll the clear coat out very much to try to stretch the coverage. You will get a much shinier finish that way.
Hope some of this helps. Good luck
