Buttons from the Design gallery are "soft-grouped". This keeps the MouseOff and MouseOver layers cemented together so that they can be moved as a single group. One additional feature of soft groups is that the text for both layers are smartly linked together. That is, if you change the text on one, then it automatically changes the text on the other. Text color, font, and size are a different issue, however — they continue to function as separate elements.

If you want to change the font color on the mouseOff layer, then temporarily disable mouseOver visibility and pickability in the Layer gallery. Highlight your text, pick your color, assign "set fill color". The text color for the button label on the mouseOff layer will change.

Do the same thing for the mouseOver layer. First temporarily disable mouseOff visibility and pickability in the Layer gallery. Then, adjust your text color.

Once you have your navigation set up the way that you want, you can add a new page by simply menuing Edit > Pages > Duplicate current page. Your navigation (and all other elements) will be duplicated on a secong page. If you'll Ctrl+mouse-wheel), you can zoom in and out on your full list of pages.

Like anything else, you can "reach the point of no return."

Like anything else, the more effort you apply to any endeavor, the easier it becomes. Xara Web Designer is substantially simpler than many alternative web authoring tools.

edit: Note that short of ungrouping, you can 1) turn off layers of elements that you don't want to effect (as noted), then simply Ctrl+click to select an internal component. Watch the status line at the bottom of the screen as you move about and pick.