The AV soil with a bit of added perlite is fine. No root powder.
Now, regarding straight peat moss, if you ever use it, remember that it's acidic. AVs prefer a higher pH, so it's best to add a bit of dolomitic lime or something. The pre-mixed bags of non-soil peat-based potting mix are usually already adjusted.
As for pots without drainage holes, they are ok to use, but be careful of several things.
1) add drainage material at the bottom. It really helps. There must be something - in a pinch, a layer of perlite will do. Since you will be watering carefully - see no. 2 - it won't float to the top.
2) Water carefully. If you drench it, you'll have a bog and AVs don't like bogs. If you let the AV mix dry out completely, it will be really difficult to get it to absorb water again. The thing with peat mixes is that they can turn to brick. I once put a pot of said "brick", complete with an AV, in a bucket of water for 2 hrs. The center was still bone dry.
3) Fertilize sparingly. Since no water is flushed out, the fertilizer and salts will accumulate and burn the roots.
4) Change the soil frequently, for the same reason as number 3. I have some streps and Chirita tamianas in pots without drainage, and it's been 4 months... and the soil has encrustation on the top, and needs to be changed. To some degree, it depends on how hard your water is, but also fertilizer is a real issue. Actually some orchid growers report that even with reverse osmosis water (which is basically totally free of minerals) they still get salt buildup.
