pot size and medium

[kvet]

Hi there!

Would someone kindly help recommend a pot size, and let me know if I can use orchiata SUPER size (3/4"-1", it's large) on its own? And can I wait 45-60 days to do this?

Key points:
- each orchid remains in its original, 4" plastic pot, now three years in May
- bottom of each plastic pot was cut off
- one big ceramic pot was filled with medium-large orchid bark from the nursery (Uni-grow or something like that)
- the three plastic-potted orchids were half-buried into the bark
- I understand as a general rule with orchids, it's best to repot not when they bloom, but rather when there's growth
- I've read it's okay to repot phals when blooming
- all three orchids had a mild mealy bug problem December-February. With persistence, I have not seen a mealy bug since February 15!
- dendrobium is 30 days into blooming, and has a new growth (I cut a notch into the pot to let it grow last week)
- phal also 30 days into blooming, second spike appeared a couple weeks ago, no plant growth
- phal's roots circle the entire pot
- zygo appears to have new growth and new roots

Photos of the den and zygo growth attached. You can see picture of the pot with all three orchids in post #5 here: multiple orchids in one pot, one has mealy bugs

I'm a little confused as far as re/up potting at this point for the dendrobium, it is blooming *and* growing!

Given the new growth, and three years in the same medium, and outgrowing their pots, I think it is time to repot. A member here was kind enough and willing to help with this in person, however, that's a no go until the shut-ins are lifted. Since I'm a little afraid of messing this up given the sentimental nature of the plants (don't care about the pots), will it be too late to repot them if I wait another 45-60 days?
I gave each pot a gentle tug to see maybe I could just lift them out, but it appears roots have grown down into the medium as well. Given this, I have no idea what sort of pot dimensions I should look at.

With the roots growing downwards an unknown about, how do I know what height pot to purchase? And diameter 5" or 6" or larger?

Also, I have ~18qts orchiata large bark remaining. It was an impulse buy. I had large perlite to match, but ended up using it in another project. Can I use the bark exclusively? Should I mix with equal size perlite and/or lava rock?

Thank you for your time, hope you are all well