If the module is requested as display=modulename, the page 'page.modulename.php' will be INCLUDED (this has not changed).
However, a significant change that you should be aware of is that you should never do any processing of POST/GET in the page.whatever.php file. The page is ONLY for displaying information, and should not contain any logic. A simple way to keep this distinction is to only write a stub for the page
Use the BMO Hook 'doConfigPageInit($pagename)' to process any variables. This is guaranteed to be called before anything else, including other hooking modules, on a page load. Note that you do not need to explicitly say that you want to hook yourself, this is implied in every module.
Failing to create a 'public function doConfigPageInit()' will result in an error being printed at the top of the screen every time your module is loaded.