Outlook API via Graph

Question

Hi We have created an app in Azure to add to our omni channel inbox. Simply we want to allow our users the ability to add their outlook accounts so they can read and reply to customer messages with their own email but at the same time have this integrated into our communications modules so they can also see Whatsapps, SMS and social messages from the same user.

I have two questions please:
With this App will we need a microsoft partnership centre ID? It mentions something about after 2020 things will change and end users can't validate apps without one.

We need to add Oath to our application so that the user is able to sign into their microsoft account is this all done through the registered Apps platform in azure ?

Apologies if this are basic questions but its our first time working with Azure and the landscape is a little confusing.