Can't say if it's a definitive answer but the SEO bloke I work with on a client's site separates keywords/phrases with commas, description is around 150-180 characters long, keywords I believe could be up to 900 so I doubt you'd ever fill that. Description and keywords should be unique per page if you're going to use them. Google will read the description, Yahoo will read both (although how much weight it places on them who knows).
There's no harm in adding Author, Copyright etc. We also usually have
<meta name="robots" content="index, noodp" />
<meta name="distribution" content="global" />
<meta name="rating" content="general" />
<meta http-equiv="Content-Language" content="en-gb" />
<meta http-equiv="Content-Style-Type" content="text/css" />
<meta http-equiv="imagetoolbar" content="no" />
<meta http-equiv="imagetoolbar" content="false" />
<meta name="MSSmartTagsPreventParsing" content="true" />
Again no harm in having them providing you don't change the robots meta tag to include nofollow!