Sure:
1) If you only need to change this in the front-end display, it is quite simple. Just open standings.php (or whatever you renamed it to) and search for:
<strong>RF</strong>
and:
<strong>RA</strong>
Then replace the labels as necessary.
2) I don't have specific docs on this, but if you look at the code in standings.php, all of the database retrieval stuff should be left as-is. All display stuff can be changed as much as you want.
The original intent of standings.php was for it to be a framework and thus there's no reason why the different implementations of the script cannot look unique. One day, in the very far future, I hope to make it more of a template system that properly separates content from design.
3) See this topic about making the default sorting method something other than winning percentage. After doing that, if you want to remove that field completely, you can first remove the heading for it:
<td><?php if ($standings_sort != 0) print '<a href="' . $_SERVER['PHP_SELF'] . "?conf=$confid&sort=0\\">"; ?><strong>PCT</strong><?php if ($standings_sort != 0) print '</a>'; ?></td>
Then remove the two entries for it:
<td><?php print $winningpct; ?></td>
To top it off, you can change the default sort order:
default: // Sort by winning percentage
$standings_sort = 0; $sort_order = "winningpct DESC, teamorder DESC";