Spiking or blooming?
 

My Dend. Kingianum is showing some unusual growths. It is sending up what look like violet leaves from some of the bulbs, while another one has what looks like a flower with roots at the top. Is this typical?

I have not watered it in several weeks, per the seller's instructions to give it a dormancy period; should I continue this or begin lightly watering?

The 1st picture looks like a normal new growth (cane or pseudo bulb) from the base. The other one on the old cane is likely a keiki. These commonly grow little babies on the old cane.

Since it is summer in Canada, did the grower mean for that dormancy to take place now? Many Den's including kingianum need a cool dry period in winter to bloom and that is the dormancy I would think the grower is referring to. In the heat of summer is when they will be actively growing and need a fair bit of feed and water. I would water it unless the media happens to be quite wet still which I can't see being the case after a few weeks.

I think he said it was still on an Australian growing schedule because of when he planted it. It hadn't done anything until I stopped watering it, so the dormancy seems to have worked. I know the leaves it has are still very firm.

I am no expert but warm sunny weather means the plant will want to grow and in order to do that it will need food and water to supply it for photosynthesis to happen. It will become desiccated and struggle if kept dry for too long.

Time to water, then!

If it came directly from Australia just recently you may not get blooms the first year as it adjusts to our seasons. I would just concentrate on growing good healthy canes for now.

One place I found recommended removing the keiki and growing it separately; should I do that or leave it for now?

As you have said, time to water (and fertilize!); cool the plant down and water sparingly from about the end of October to the end of February; most of them bloom sometime between December and March.

Keikis should be left on until you have a minimum total of 3 inches of roots growing from it. It might be one long root or 3 inch long roots or similar. Some kingianum growers leave the keikis on and they bloom where they are along with all the adult canes. It makes for a good show that way too.