
Explanation

Box 1: B1
B1 (Basic) would minimize cost compared P1v2 (premium) and S1 (standard).
Box 2: Cross Origin Resource Sharing (CORS)
Once you set the CORS rules for the service, then a properly authenticated request made against the service from a different domain will be evaluated to determine whether it is allowed according to the rules you have specified.
Note: CORS (Cross Origin Resource Sharing) is an HTTP feature that enables a web application running under one domain to access resources in another domain. In order to reduce the possibility of cross-site scripting attacks, all modern web browsers implement a security restriction known as same-origin policy. This prevents a web page from calling APIs in a different domain. CORS provides a secure way to allow one origin (the origin domain) to call APIs in another origin.
References:
https://azure.microsoft.com/en-us/pricing/details/app-service/windows/
https://docs.microsoft.com/en-us/azure/cdn/cdn-cors