i can’t remove the borders or for that matter even find the borders in the css.

I see border color #ccc mentioned in your css several times.

an example of the problem is that the header is supposed to stretch all the way across the page.

A) Your header does go all the way across the page

B) how is that relative to your border problem?

Your navigation menu in the header looks like crap in firefox. Looks great in IE. Increase your nav width to 450.

Difficult with a link to your site. However most themes have a “post” div class which all posts are wrapped in. Therefore adding this to the bottom of your style sheet should do the trick:

.post a {
  color: #000000;
  text-decoration: none;
}

This will make all links in a post black with no underline. Change the hex code to a colour to suite your needs.