Answer #1:
Use BeforeHeaderRender event and change e.InnerHTML (or BeforeTimeHeaderRender in DayPilotScheduler).
Answer #2:
Since 4.1, it's possible to change the "Scroll down"/"Scroll up" texts using ScrollUpLabelText and ScrollDownLabelText properties. You can also turn it off using ScrollLabelsVisible property. See also the release notes for
4.1 (
All texts localizable section).