I can't find your problem with international shipping. I attached a screenshots of the quote options output and compared the priority mail quote with USPS online quote tool. It looks like it's all correct from what I see.
Perhaps you should set the debug option to "XML Dump" in shipping module admin. Then put the contents of: http://pathtoyourzencart.com/uspsSend.xml in a post here.
Remember to remove the xml files and turn of debugging afterwards. Also remove USERID="asdfjkhsadkjfh" from the request before posting here.
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