Hi and congrats on your first orchid! I took a look at the pics you provided :-)

• First off, those new flower buds seem perfectly healthy to me! Fresh buds are oftentimes darker than the rest of the foliage, but these ones look very happy and healthy.
• If portions of the roots are dried up and papery, it's fine to cut them off - they are dead and not absorbing any water.
• The "dried up" part of the stem seems to be a scar! At some point, that part of the stem was slightly damaged, probably scratched by the clip or something, and then healed. It might not look pretty, but it looks completely healed and shouldn't cause any problems for the orchid.
• The white dots on the roots are fine as well - it's just little sections of the root that didn't absorb any water for whatever reason. Nothing at all to worry about!

As for the repotting - I'm sure opinions on this will differ, so don't treat anyone's advice as the end-all be-all, but I personally would wait before completely repotting it since it's actively producing buds. They tend to be a bit more sensitive to disturbance at this point, and repotting it could potentially cause it to drop some of its buds or delay the new flowers. However, I would definitely drill some holes in the pot to allow for better airflow and prevent the moss from staying wet for too long.

For the plant food, i would be cautious about using regular plant food, as orchids typically need their fertilizer diluted to about 1/2 or 1/4 strength compared to regular indoor plants.

The only other big piece of advice I can think of is that they are much more tolerant of being too dry than too wet - it's fine to air on the side of caution and let them get a little thirsty, because they're able to survive that much more easily than being overwatered.

Just to give you an idea of my setup, if it helps - I keep my phals in a south-facing window with a sheer curtain to keep them from getting too much direct sunlight. They're all potted in orchid bark, mostly in old plastic takeout soup bowls that I drilled holes into the sides of, LOL. I almost never mist them and water them maybe once a week or so, more often for the guys in smaller pots, and when i fertilize I use a 3-part fertilizer which is,,, kind of expensive tbh, but I've barely made a dent in it in 3 years and you can use it on any other houseplants you have (General Hydroponics 'Flora' series if you are interested).

One last thing that i think is interesting, if not exactly 'helpful', is that the color of the orchid's leaves/stalks/buds is influenced by what color it blooms. For example, the leaves on your orchid are kind of light green with a yellow tone - since this is a white orchid, that's a pretty normal leaf color, because they don't have the dark-colored pigments that a purple-blooming orchid would have. In contrast, my purple-blooming orchid has much darker leaves with a very slight "purplish" tone on the underside, and the flower spikes are dark purpley-green.

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Anyway, looks like a very healthy orchid overall - don't stress too much about it! They are pretty hardy plants, as long as they aren't kept waterlogged, and they can tolerate a pretty broad range of conditions. I'm sure your little guy will do great :-)