repotting phal?

[K.Veren]

Hi all, I just welcomed a new member to my lovely orchid family-- it's a truly spectacular white orchid with tons of buds (30!), but it seems a little root-bound and I'm terrified as I face repotting. When I look at the pot all I can see through the plastic is roots.
Should I repot? Or should I wait? When is the best time?
And should I get a larger pot, or should I just trim off some of the old roots and keep the same pot? If I should trim, how do I decide what roots to trim?

as an aside, one of the smaller buds at the edge of one of the branches leading off the main spike just shriveled up and fell off this morning, is it possible I'm killing my new baby? I checked and the root system looks healthy with no sign of rot; is it something else? Or is it just normal?

Thank you all SO much for all your help; your guidance has led my other two orchids (one on the verge of dying when I got it) to sprout two new leaves each!