Hi Amey - I am seriously no expert on slippers - paphs or phrags - everything I know comes from just a little experience, and a lot of reliance on the real experts - Geoff Hands is my go-to man on this one - and I read the books to the trade (i.e., slipper orchids manuals by well-known authorities/breeders), and have known one truly gifted hybridizer personally. Anyway, I can tell you what I've learned to do. First, I do repot my slippers in S/H as soon as I can - they are particularly suited to it. They live in front of my south-facing window, but it has an overhang above it that shades them more in the summer than in the winter. Phrags get brighter light than the paphs, but somewhat less than catts, (and green-leafed paphs get more light than the mottled-green ones, if that helps at all. Oh, and my paphs seem to do fine under grow lights, but I keep the phrags much closer to the natural light. When I see a particularly large plant, I always check for old spikes, so that I know this particular plant at least has bloomed before. Sometimes a large plant with no signs of blooms can mean it is going to be a reluctant, or lazy, bloomer - and if it shows no signs of having been recently repotted, I usually find that it has become seriously pot-bound and many of the new roots have already suffocated and started to rot - which means that much longer to recover from a good, thorough cleanup.
I suspect that a north/east window will not be bright enough, but I honestly can't say for sure. Repotting, especially in S/H should help correct the dehydration- one thing I can say is that all my phrags have very healthy new growth. The crucial thing for me to do is remember to water them, because they take such good charge of themselves. Oh, and I have all my slippers near the humidifiers, where the humidity is about 80%, and near the fans, where they get constant air movement. They stay around 68-74 degrees, give or take a few, because I can't manipulate their environment beyond placing them where they are, and misting them every day for goo measure. Last year I made the mistake of putting my paphs outside in the shade - too hot, too much light, too dry, etc - not a good result.
I know you have far more knowledge and experience than I do, so I feel a little funny about even trying to explain why I do what I do - within a very short amount of time, you'll have figured it all out for yourself.
(Oh, one last thing - phrags are very sensitive to water quality - rain water or reverse osmosis is best if your tap water isn't pH-balanced, and relatively pure.)