Will iOS 10.1.1 work well (i.e. sync, etc) with OS X Yosemite? I have a mid2012 Mac mini running Yosemite and Pro Tools that I don't want to upgrade OS, because that would require a Pro Tools upgrade.
Yes. Latest version of iTunes is needed. Currently it requires macOS 10.9.5. At this current rate, Yosemite will be supported until iOS 12 is released.