Scarred roots, yellow wilted leaves, moss questions

[Mangomama]

Hi,
I have 3 phals and just added a 4th to my collection today since the 3 have finally finished blooming and I couldn't resist getting a new one to bloom for the winter. I guess it really is becoming a collection!

I have several questions....

On my oldest phal, which I bought about 1.5 years ago, the surface of the older roots near the top of the medium have become brown and scarred. Is this normal or is it an indication of something? The roots otherwise seem really healthy, and the plant seems really healthy. Leaves are dark green and stiff. However, it only put up one short spike this spring with only 3 or 4 blooms. It grew a lot of aerial roots this summer.

On another phal, which I've had since early spring, the leaves seem really healthy, but the small lower leaves are yellowing and limp. Is it because they are not getting any light under the larger leaves? Why are there little leaves under there anyway, as I thought new leaves grow from the top....

Finally, my new purchase is soaked in moss. By what I've read, it seems I should replant in bark, which is what I am going to do tomorrow. I am also gleaning from info here that it's okay to repot while in bloom, right?

I am also thinking of reusing the moss for the one orchid that I repotted in my new cut-out ceramic pot. I am thinking that since winter is very dry here, that it will do better with the moss?

Thanks!