First thing you need to help recover your orchids is patience. A lot of it.
For the dendrobium, i agree with Jordan to remove the moss from the pot, as this will worsen the condition. Dendrobiums are hardy ones ( in my opinion) just water it regularly.
For the vanda in basket, you can soak it in water even for hours, may also add some rooting hormone during soaking. and keep humidity hight. ( I myself got trouble with humidity)
For your new plants, repot them when you see "baby" with coming out, better if the "baby" got new roots shooting out already. This will make establishing the plant easier.
Good luck!