I started my batch; filled the primary to 7 gallons to compensate for the sludge (since the carboy is 6.5 gallons). I used EC-118 yeast, and pitched the yeast after adding the water (only deviation from the recipe posted, all other ingredients were added at the point it was heavily concentrated). A couple notes:
Since the recipe didn't call for Campden tablets at the start, I didn't use any. That seemed wrong to me, but I assume the boiling water used to kill off the preservatives handled that, yeah? Otherwise I'll cross my fingers.
I used a 48oz can of Syrah concentrate instead of the welch's. Though a smaller amount, this led to a starting SG of 1.12 (I also overcompensated with the skittles and undercut the sugar slightly)! Between that and the strength of the yeast, I plan to ferment to dry and have a strong batch (around 17-18% by my calculations), then cross my fingers and backsweeten if necessary, but I think dry will be sweet still.
One last note--the top scum stuff started before I pitched the yeast. I think it started from the pectic acid reacting with the ingredients in the skittles (most likely the hydrogenated palm kernel oil, as it looks like fat residue). Whatever the reason, after cleaning the bowl I used to mix the initial skittle/boiling water, I think it's a really good thing that it forms during fermentation. I plan to skim it off after fermentation starts to slow and continue to until it doesn't form, then transfer to the secondary (and possibly just bulk age from secondary). If it is the oil, hopefully it doesn't turn rancid (though based on the fact that most of you never skim it, it's probably not that big a deal).
Also, once it's done I'm going to try to make skittle skeeter pee. Just because it's fun to say.