DJ Event Client Manager

If you were a DJ and needed to communicate with clients about their date, how would you do it? Can we leverage the power of the Spotify and and other music API's to let users build playlists within a screen or from their spotify app on the go? A client portal to login and administer different aspects of the event like schedule and lighting, etc. Clients would first fill out a basic form about their event, book a date, and then upon email confirmation and credit card deposit charge, be taken to the client portal. The client portal can then offer collaboration between not only the DJ and client, but they can invite others to collaborate on ideas. It needs to be able to be simple intuitive from the smallest birthday parties, to weddings and Company Award shows. Extremely customized based on the event- wedding, wedding and reception, proms, etc. What are your thoughts about the spotify playlist maker? any alternatives? I've always liked facebook and google logins sound great as well. Is it possible to get demographic and personal info? can their likes build an automatic playlist based on their individual musical likes? also as much personal info and demographic info makes it easier to tell what kind of person the DJ is going to have to adapt to. It all needs to be on a very responsive framework. An app may be down the road for this project. This is for a client, but I want to package this up as a plugin and several addons for resale. This project doesn't even have a real concept or layout as of yet. I've researched what's out there and the majority of scripts out there don't manage the relationship, just the initial contact. Thanks for your time and input.