Honestly, Seattle is about the worst orchid vendor in the USA. Besides the inconsistent plant quality (and rootless plants is just the tip of the iceberg in regards to the crap they'll send in my experience) they are notorious for sending misidentified / mislabeled plants. Plus they don't take any responsibility for problems and will lie to you directly when confronted about it. Anyway, I'm done ranting.
As for your Phrag, what I have success with is to pot them up in normal potting mix, perhaps with a bit of sphag on top if that suits you. Then I'll slide the pot and plant down into a bread bag, open end up. I make sure to keep water off the leaves, and typically leave the top open for air exchange. This is basically an inexpensive personal humidity tent for the plant (assuming it's small enough to fit in a bread bag and assuming you have bread bags available, but really any mostly transparent/translucent plastic bag will work).
I do usually give my recovery plants some kelp or superthrive type products, but I'm going to be honest and say that I'm not really convinced these types of product are the super stars they are sometimes presented as. So, if you don't already have them on hand, don't bother wasting money on them. You've already been screwed over once, no need to waste more money.