As Amy told, I'll be helping you during your task. I appreciate your contribution to the Joomla! and open source world very much. This is how open source survives: with the help of volunteers contributing generously.
First of all, I will mention about the new and more object-oriented (thus, more convenient) way for developing modules in Joomla! 1.5. You can see how it works in most of the core plugins or in the module tutorial in Developer's Wiki
I would rather use this way as it's easier to maintain the code and add new functionalities. And as we are a big and international community, your module should use language files in order to be translatable. So people can use it in their own languages if they want. You can take look at my plugin called Title Manager
about how you can implement multi-language behavior.
If we turn back to the code, first thing I would like to say is your way of getting _uacct code may cause problems. For example if there is white space before the '_' character, you can't get the needed data. So I would prefer using _uacct code as a parameter instead of splitting it from the whole code block. This would also be quicker.
Secondly, Google Analytics has SSL support and the script url is different for this option. You can determine the SSL need with a parameter in backend and then use the global variable of PHP -$_SERVER['HTTPS']- to feed the correct URL.
And there are some missing fields in your XML file like copyright and licence. You should fill them.
If there's anything I can help, don't hesitate to ask here and please let me know when you have a new release.
Thank you very much for your efforts.