it could be that your php server has the magic_quotes_gpc turned off causing issues.
try adding the at line 1 of the admin/producs_insert.php file:
I have just tested both 3.0 and 3.01 on my system and cannot reproduce the issue in either.
as for updating: yes, the update will override any modifications you have made to the pages.
In the 3.01 update, every page was updated, so it is not possible to update only the problem pages.