1. Anything can be a "default", you just need define a class, define some properties of said class, then apply the class to any object you want to use the stylings therein.
2. This is possible, though you will need to use empty elements, which I am not that big a fan of. Take, for example, this code (all inline styles to shrink the code):
Code:
<div class="button">
<p style="display: inline; background: url(left.jpg) no-repeat;"></p>
<p style="display: inline; background: url(repeat.jpg) repeat-y;">Content</p>
<p style="display: inline; background: url(right.jpg) no-repeat;"></p>
</div>
The "display: inline" style is to make them stack horizontally. <p> will normally not do so, and due to this it must be forced.
3. That's a sans-serif default font. It appears to be Arial, at 10 point size.
Jam it back in, in the dark.