Hi,
What would be the easiest way to include a new field for a homepage link? Can I make use of any of those hidden inputs?
that's not such a good idea, because these fields are for spam-protection.

Even if you use one of them the data won't be stored anywhere.
It' not so easy to add additional function to an existing module.
Getting the input field for the data in the view.php (or whatever this file is called) is one thing, but you must store this data in the database - that means you have also to touch the add.php or save.php - you have to extend the database-table with a new field to store the data and last but not least you have to get back the data from the database to display them - you have to touch the view.php.
Depending on your needs you have to touch additional files e.g. to display the "new" data even in the backend.
Doing all this you should have a little bit experience in PHP and MySQL and you should think about the fact, that you modify core-files which will be overwritten by the next update ...
Regards Bernd