Yes, indeed, it does come with instructions. It instructs the user to deflect it off of a vertical surface to gently disperse over the flaming liquid. It also includes a warning basically saying: don't spray this directly as the liquid, or else you'll just get the hot flaming liquid everywhere!
With regards to the contents of the foams, it seems they're are a plethera of kinds, as are the dry chemical. The dry chemical is useful, as instead of removing 1 or more of the 3 'sides' of the fire triangle, it breaks the continuous chemical chain reaction that allows it to exist as a fire. So that's great; There are lots of good extinguishers;
Looks like the bottom line is: Just have one to keep your house from burning down...