Can we rotate the axis annotations to be parallel to the feature lines?
Yes, it is under Edit Attachment.
It use the old dialog so it should be the same for all versions.
In Creo, be in the Annotation tab and highlight the axis. RMB and select Edit Attachment. in the menu that comes up, select Enter Angle. The Angle you enter is relative so it cumulates as you enter values.
You can also select another reference for the axis to be "through" - in this case, the axis at the other end of the slot should do what you want.