I think the Administrator Policy and Policy Template are read-only. That might explain part of your problem.
In any case, they should never be altered. You should always duplicate them and alter the duplicate. It sounds like you're still looking at a bug in the export process, though.
In theory, exporting a custom Policy would have just the set permissions set in the XML file.
As a workaround, you might be able to do what you want with a couple of snippets using something like this (untested):
<?php
/* Export MyPolicy */
$policy = $modx->getObject('modPolicy', array('name' => 'MyPolicy'));
$fields = $policy->toArray();
$data = $modx->toJSON($fields);
$fp = fopen('mypolicy.txt', 'w');
fwrite($fp, $data);
fclose($fp);
<?php
/* Import MyPolicy */
$data = file_get_contents('mypolicy.txt');
$fields = $modx->fromJSON($fields);
unset($fields['id']);
$policy = $modx->newObject('modPolicy', $fields);
$policy->save();
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PLEASE, PLEASE specify the version of MODX you are using.
MODX info for everyone:
http://bobsguides.com/modx.html
