Slant, are you changing your templates editing the files on the server or via the administration?
To change the "sort by" items you need to edit them directly in the database using phpMyAdmin or something like that. There are already some threads about that, search better =)
As for the empty extra field, just copy some extra item code from your PP and use it in RP.
Something like:
if ( !empty($extra1) ) {
echo<<<PPPRINT
... your desired content ...
PPPRINT;
}
You need to edit the var name, of course =)