I made up some Formulary MCM-100 a couple of months ago, and the PPD looked exactly like you described. The instructions suggested dissolving it in water at 125 F/52 C, which is what happened. I would say that grinding PPD was not a good idea for health reasons, and it is not necessary anyway.

Here's what the Formulary instructions say about cleaning up:
"Clean the work area very carefully using soap and water or with a 1% solution of hydrochloric acid (about 3 ml of concentrated acid per 100 ml of water). The hydrochloric acid converts the p-phenylenediamine to a water soluble salt making the compound easier to remove."

I'll be interested to hear how your 777 tests go. www.pofig.net has a formula for a PPD-glycin dev (S-3) which I'd like to try sometime (though I'm not sure why). Have you ever tried the commercial 777 from Bluegrass?