Change PHP codes in my new website

my new site [login to view URL] needs some editing. 1) currently when you upload files, it stores the file as [login to view URL], with xxx being consecutive numbers. therefore, you can type a random number like id=24 and link to a randome file uploaded. for security reasons, i was wondering if anyone can change this to a "random number generator" like j2h2ijrfhs, etc etc instead of consecutive numbers. 2) this one is easy.. add a like button for facebook onto the website 3) another easy one add a contact us page 4) add a contact form for customer support 5) add a paypal donate page with button for donations 2-5 should be fairly easy i can do it myself as well but really looking for #1 to be done.