It really needs some sort of automated testing. multicheck.php alone contains multiple regexs and a significant volume of code that examines html in string form looking for a redirect or signs that the site is a Moodle install. All of this is eminently testable.

The functions will need to be moved to a lib file (or similar).

If we can also get rid of the 11 global variables that are being used that would be no bad thing.