Yes that is a lovely dendrobium plant. The spike has begun drying out. Myself; I let the spikes finish drying before I cut them. It's up to you when you cut the spike (some don't like the way spent spikes look). And the window should be fine until outdoor temps warm up enough. Don't let your dendrobium get cooler than your phals, but you can let it have a more sun. Dendrobiums also like tiny pots. I have a few that are over three feet tall and still in the same size pot yours is in. The way to keep them upright is to put them in a clay pots as you have done. I would hold off on watering for a week or two, it will encourage new root growth.
That window looks like a nice haven for plants...good luck with your new Dendrobium.