I just finished cleaning up my patio after laying down cobblestone pavers and using polymeric sand. It was my understanding that there can't be any sand on the pavers. I didn't realize that also the gray dust (guess thats some of the polymer) needs to be removed or it will form a residue on the pavers, which has happened. So, first question is what is the best way to remove this?

Second, I've noticed that there are a couple of ways that water wants to drain off the patio. When the water flows these ways, it takes the sand with it. Is there a way to build up the sand in these areas so it will 'cure' and remain there?

Thanks!!!!