I got the YouTube issue fixed (the issue where the "Watch in High Quality" option, noted above, was completely missing).
Download the updated YouTube.apk here:
YouTube HQ Hack - Page 6 - xda-developers
Then follow these instructions:
YouTube HQ Hack for Nexus One | xda-developers
Worked perfectly, and now it defaults to high quality when starting a video. It still has a menu option to "Watch in Normal Quality" if you do so desire.
Whew! One issue down, two to go...
1. Proximity sensor while in-call
2. Sound with boot animation
Once I get those two things, I'll be set until Froyo gets perfected