I'll leave most of this for the experts to answer, but what I do is give all of the aerial roots a good misting every morning (and usually another in the afternoon). Since I know that orchids are air plants, as long as there are some roots going down into the medium, I don't worry too much about aerial roots (until they threaten to take over my room....... sort of like Audry in Little Shop of Horrors.. LOL).
The misting really doesn't take all that long to do, but I only have five orchids........ oops, make that seven now. I had to divide one, and I removed and planted the keiki that was on my 'Mary Motes' . Now let's hope the two new ones are happy in their new homes.