So I'm happy to report back that changing the engine mount has COMPLETELY fixed my issues. I can't even begin to describe how different, and better, the car is now. The drone at 3000 rpm is gone. All I hear now is air rushing past the A pillar and the tires humming on the asphalt. And, most of the little buzzes and rattles I was complaining about are gone too. At idle, the car is just silky smooth. Even my wife, who is typically oblivious to all things mechanical, could not believe the difference in the car. The old passenger side motor mount was completely shot. I got the new OEM part online from Tousley Ford for about $90. Without reservation I can say that is probably the $90 I've ever spent.
The best part is changing the mount is a completely DIY friendly project. It took me all of 15 minutes start to finish. I think changing the hydraulic mount should just be part of the routine maintenance for the Focus every few years.