Brown Areas Showing on Aerial Roots of Phal??

[Higgins23]

I realized I probably posted this in the wrong forum (beginner discussion):

Hi all. I got a large phal back at the end of March of 2013. When I got her, she was just at the end of opening up all her flowers (she has one spike). The flowers have been gorgeous since then. A few questions, though:
1. How long do flowers typically last? She dropped her first one last night. Sound normal?
2. In just the last few days, I noticed brown areas/spots appearing on the tops of the arial roots (see before and after pics attached. I could only attach the before to this post. Will post reply with after pic. The before was taken in March. The after was taken today). Should I be worried about this? Over watering?
3. Just this week I've noticed clear sap forming on the spike just around the base of the flowers only. I've read that this can be a sign of a happy phal, but I'm concerned that it could be linked to the brown spots on the roots or dropping flowers??

I'm not seeing any bugs. I've been watering about once/week (soaking) as long as her pot is dried out. Haven't been giving any food or boosters, just water. She hasn't been repotted yet since I got her because I was told to wait until she was down flowering.

Thoughts? Thank you!!