for #3, if you entered just the www.domain.com, instead of the full URL, then you would want to do:
echo("<a href=\"http://$row[link]\">$row[link]</a>");
I prefer to have 2 columns, one for link url, and one for link text.
echo("<a href=\"$row[link_url]\">");
if( empty($row[link_text]) ) echo($row[link_url]);
else echo($row[link_text]);
echo("</a>");