(Bing Ads API) What API operations will my app require?

Hey community,

I'm doing a bit of discovery work for an application I'm building. I'm very new to the Microsoft Ads product so anything helps.
My goal here is to find what API operations I would need to in order to accomplish what I'm looking to build.

A quick summary of the application here:

The app will allow the user to push an email list to a Microsoft Ads Account Audience (only Remarketing List Type). The emails of which are collected from the user’s created form on our platform (think ecommerce type collection forms).
The emails will be pushed from our app to the user’s Audience via an automated job running every hour. The application will take the user’s Developer Token, Account ID, and Customer ID associated with their Microsoft Ads Account.
With this information we should be able to display the user’s Audiences and also display the user’s Managed Accounts’ Audiences as well.
The application should also allow users to create an audience (Remarketing List Type)
In short, this application creates an automated way to push emails collected from our service to a user's Audience (Remarketing List Type).

I've read through the guide found here.

I'm not really clear on which operation I would use to get the user's associated ad accounts and the ad accounts they are managing. I'm thinking the operation found here would account for this issue.
Are there additional operations that are better suited for the issue?

For creating a remarketing list type audience, I've found this operation.
For fetching all remarketing list type audiences, I've found this operation.

I'm a bit lost on uploading the email list to the remarketing list type audience. Any guidance is appreciated.

Again, thanks for any help or guidance.