Help needed from a total newbie!

[Newgirl]

Hi folks! I am totally new to the world of orchids. However, i have had an Phalaenopsis orchid for over 10 years now and even without taken proper care of it, it still lives and it even had 3 babies which i 'planted' on their own after they fell off the motherplant

However, i have decided to give them a little better care and started to watch tons of videos on Youtube. There are though a copple of issues i cannot seem to figure out and i could really use some help.

1. This orchid has been in a not see through pot in regular soil for years. The roots have turned this colour. Are not mushy or soft. Still viable or should i cut them?

2. Will yellow roots turn green if they are exposed to light long enough?

3. The roots have white spots on a lot of them. Is this fungues or normal? What should i do? There is nothing moving so no bugs and i cannot scrape them off with my nail.

4. The stem is incredibly long. Should i leave it like this or cut anything from it? There are still a lot of roots coming from the lower part but are the roots viable?

I have bought a see through post, hydrolic pellets and orchid bark. I cut away a lot of dried out pines and roots already and this is what's left.

Please advice some more! Thank you so much!