Root rot vs. dehydrated, and new orchids with crazy roots

[Piper23]

I took everyone's advice that my orchids were dehydrated and I slightly increased the frequency of watering based on the change in the weight of the container. Most seem to be fine (pics attached), but one developed root rot and died.
Advice for avoiding root rot while still providing adequate hydration?
There is a picture of the potting media that came with the plants (they were gifts). Better options?
They are in a window that faces east here in New England.

The other pic is of two that came to me today from someone that bought them and left them be. How do I start to take care of these given the crazy-long roots?

All and any advice is welcome!