Yes, additional properties for colors would have to be applied in the extra properties in every style if you wanted them to change for each style.

The HTML you put in will be the HTML you get out, if you insert HTML with errors (including improper nesting) you'll get the same output; I've seen some forums putting a closing tag before an open tag and assuming things would "just work" such as:
Code
</p>
<p>blah blah blah

This is especially bad form when things are approaching a "strict" working model, whereby dirty code just won't function in some browsers/on some servers.