Pickling lime can be had in a lot of grocery stores, somewhat seasonal for some, but mostly now as fall approaches. It'll be in the canning area. Only two brands I know of Balls and Mrs. Wages, either will do the trick. I've heard they can also be purchased online.

The LFS won't carry it, instead they'll likely carry Kalkwasser (or something similiar as a calcium suppliment, of course they'll want to sell you that, it's pretty much the same thing, just priced upwards of $12-$15 for a 6-8 ounces, versus $1.50 for a 1lb can of pickling lime. Not sure if it's as effective as the pickling lime or not as we personally haven't tried it.

On the zoa frag, they can be tricky, if the frag is too smal to split again to get at the aptasia easily, do your best at pulling as mush as you can of it off with forceps, tweezers, or a hemostat, get as much as you can, it'll very likely grow back but may gain you some time for the zoa's to grow out a bit.