-- For the username, would you try using '.entry .poster a' as your selector? I see you've got it as #entry .poster in your code.

Footer bkg:

.entry .footer {
background: url(URL) no-repeat top center;
padding-top: 20px;
}

I think. Not sure the padding is needed. Depends on where you want your border to be.

-- Space between entries:

.entry {
margin-bottom: 2em;
}


N.B. Ariel and Arial are two different fonts. :)