Updates to existing website

I have an existing website built in PHP with a MySQL database in the back end. It is something like an online catalog of products. You can subscribe, add products, search them, etc. I will provide more details to the developer. I want little tweaks to be done to the way some elements/pages function and to enhance it with some additional functionality: - the registered user to get an email notification once an action is performed - a user has the ability to add friends. this is manual at the moment. I want the user to be able to add friends from the existing users. For example, my brother already has an account too, instead of adding him manually, I want to search for this name/email and with the click of a button, add him to my friends list - to add a section for Birthday alert and the user to get a notification/email when their friend's bday is approaching (bday is already recorded upon sign-up) - to add a functionality where user can elect to subscribe to a service. Paypal checkout is already implemented on the website, but this new service will have to be added into the existing logic If the developer doesn't mind doing some front-end work as well, that would be ideal. Just small styling changes and some javascript for some nice effects.