I have what seems like a zillion feet of vanilla orchid growing in my greenhouse. I actually just ripped out a whole garbage bag full. So it can be kind of weed-like under the right conditions...
They will climb up anything (some are growing up a fake cement tree), attach themselves very firmly and then send roots down to the ground. So really, the bottom of the plants don't need to be in ANY soil, bark, etc, but I do start them in a 5 gallon nursery pot with small orchid bark, for convenience. Then I can move them if I want, before they become permanently fixed to something.
Mine seem to bloom only in almost full sun. The blooms are only good for a day, and I spend a lot of time cussing when I find wilted ones. Once they set buds, check several times a day. We are at 2,800 ft, so the sun up here is VERY hot and burns them if they are in totally full sun in the greenhouse, but they do well in very very light shade.
As to care, I keep the ground around them, where the roots bury themselves, moist, and spray them every few days, especially wetting the roots that are above ground. I am pretty lazy about fertilizing. I might get more flowers if I was more diligent. Whenever I fertilize my other orchids, every month or so, I do the vanilla also, with just dyna-gro diluted to about half strength. I soak the ground where the roots have burrowed with it. The roots will fan out underground for quite a ways. I spray the plants too, but not sure if that actually does anything other than give them a bath.
If you zoom in on the picture you can see the roots attached to the cement tree. (Ignore the cinnamon tree leaves in the foreground...). The blue and yellow things on the fake tree are the nest box doors for my little parrots. Every so often I have to rip some vanilla away so they can get in.
Good luck!
Carolyn