The only modding i can see you have done is to change the design to fit your site. Lazarus can easily be integrated into any PHP page so it fits your site perfectly.
To be honest I'd say most of the files have been changed from 2.3.4 to 2.4.2 so you would have to replace them all. To hide admin.php simply rename it and then edit the config.inc.php file to show the new file name of admin. Hiding the links just requires you to edit the templates.
Sorry for the late answer but forum didn't tell me I had a new post