WordPress Site needs to work with existing PHP codes ( INDIAN Preferred)

Please read the post fully before applying. All the template replies would be ignored. We have a working website providing automatic digital downloads to the buyers, an admin panel keeps the records of user accounts with name,email,address, number of purchases etc & also sends auto confirmation mails. the website is coded in PHP. Now we wish to create multiple similar websites ( which would work as affiliates to the existing site) in WordPress with same features of instant downloads & the admin panel in the main site should work as master database so every sale & user registration should be updated to the main site with the name of affiliate site, also should be able to send confirmation mail We need some one who can provide a solution to this. We'd need the actual source code from the developer. One can tweak the PhP code to work with the WP sites or also can provide stand alone solution for instant downloads, centralized user database for all affiliate sites, & auto confirmation mails. The Instant Download files are not in same server as the WP sites the are in Media-fire server & we wish to five users 2 downloads per purchase. Please be specific on what you can do for the website when you apply for the work.