Hmm, interesting. I am very surprised to find that there's no mention in the rules about what kind of action this is.
There is precedent, however. Spreading flour or powder onto a square or space is a standard action. While it's not a RAW answer (sorry :( ), it's probably the closest you can get.
And the answer to your second line of questions is, again, sadly, not RAW. But logic would dictate any square within your natural reach. If your DM is alright with it, a ranged touch attack on a square with a 10' range increment would probably be alright, too. That follows the Thrown Splash Weapon rules.
Honestly, this is such a simple situation that your DM should have no problem adjudicating it if you give him the above precedents.
Good luck, and have fun. :)