Combining Orchiata with NZ Sphagnum Moss

[HiOrcDen]

Some of the Orchids I have purchased came in pots with a combination of sphagnum moss and orchid bark.

Some of these orchids just have moss around the base of the leaves at the surface, towards the center. So I am guessing this is to keep emerging surface roots moist, is this correct? With these, I just water around on the bark, at an angle to get towards the center underneath. Though from my experience, roots which emerge above the substrate do not need to be kept moist, especially if green.

Some orchids I got seem to be in kind of a chaotic mix of a mass of sphagnum moss with bark chips, in uneven proportions. I try to water in a similar manner as the first instance, though I'd really like to repot them in a more orderly fashion.

So the 3rd instance is something which I actually like. And that is a smaller amount of moss mixed in with the bark substrate. I like the way the sphagnum keeps the chips in a solid mass. Is this okay for all species, or only certain species?

There are two more instances I would like to ask about.

One is a pretty big Brassavola Digbyana. I bought it over a month ago and put in sphagnum moss. It seems to have done okay til tonight, and I'm starting to see a bit of darkening. I would like to switch it to orchiata, since the plant is too big for moss, I think, especially in a standard pot. Should I put a bit of moss in with the orchiata when I repot?

Also, should I put a bit of pumice, for some aeration... should the pumice be somewhat crushed/broken up a bit.

Also, my big Angraecum, which came in just under a 1 gallon pot, I have repotted to a 1.5 gallon, standard pot (no slots) It came in 100% small chip bark. However, since it's now in such a big pot, when I repot to small chip orchiata, again, should I add some pumice and/or perlite for extra aeration?

I'd like to repot the Digbyana tonight... so I'd really like a suggestion of whether I should use a bit of moss (since its been in 100% moss for a month) as well as perhaps pumice or perlite!