Are these features feasible for a custom app?

[intpprux-_4x]

Plan

Premium

Country

United States

I represent an organization [unnamed at the moment] that plans on integrating spotify's APIs for their events. I wanted to ask a few questions while scouting the APIs to make sure I have the legalities in order. 

I have 2 main questions:

1) We plan on offering our application built with spotify to all users, however they can only access the related content on our app if they have signed up for an event with our organization, and only for the duration of the event. Does this count as a commercial use of the app? I felt it wasn't really commercial, since we aren't charging for the spotify access. However, am not sure if this is locking the features behind a paywall, hence making it commercial. We aren't asking the users to pay for spotify per se, but instead only allowing users present at the event to access the content. 
I can spin this slightly differently and say: we are only going to allow users that are present in the main room that the event is taking place in to access this section of our app. 90% of the users will have to had paid for this, the other 10% will not. Does this make the app commercial?

2) We plan on allowing users to add songs to a global queue (with slightly different features + a different mechanism of ordering the songs as compared to a session, and support for a much larger number of people than in a session) available to all members at the event. Then the event manager can play the songs as shown in the queue. I noticed something of the reverse: not allowing multiple devices to play the same audio, which I understand is a way to prevent the app from bypassing a free account's status, and I don't think that this is violating anything mentioned in the terms if I allow multiple devices to control the audio on a single device? Is this right?

Just wanted to clarify that I am not trying to argue any of the usage and access rights listed, I want to be able to gauge how I should approach spotify, either as a commercial app or as a non commercial app, and also wanted to know if I require additional permissions for the second question: making a sort of a global queue.