A Web API in ASP.NET Core primarily serves to facilitate communication between web applications. It enables applications to exchange data and functionality over HTTP, making it a crucial component for building RESTful services or supporting AJAX requests in web applications. It does not typically handle user authentication or manage database schemas directly.

When multiple developers work on separate migrations, it's essential to collaborate and combine the migrations before merging into the main branch. This prevents conflicts and ensures a consistent database schema. Entity Framework Core doesn't handle automatic merge of migrations, so developers need to coordinate their efforts to avoid issues.

To achieve a redirection after a successful action, you should use the Redirect action result. It allows you to specify the URL to which the user should be redirected, typically a confirmation page in this case. The Redirect result returns an HTTP 302 status code, indicating a temporary redirect.

In ASP.NET Core Identity, the RequireNonAlphanumeric property should be set to true if you want to enforce that passwords must contain at least one non-alphanumeric character (e.g., special symbol). This adds an extra layer of security to user passwords.

In ASP.NET Core, session information is typically stored using cookies by default. Cookies are small pieces of data sent from a web server and stored on the client's browser. They are commonly used to maintain user state and session data across HTTP requests, making them suitable for storing session information.

Dependency injection in ASP.NET Core MVC allows services to be injected into controllers via their constructors. This approach promotes the use of constructor injection for better testability and maintainability of your controllers, ensuring that required services are provided when the controller is created.

To ensure that multiple entities map to a single table in table splitting scenarios, you can use the .ToTable() method with the same table name for both entities. This tells Entity Framework Core to store both entities in the same table in the database.

In ASP.NET Core, you can achieve the goal of running certain middleware for specific routes or URLs by using attribute-based routing. By applying attributes to your controller actions or classes, you can specify which middleware should be used for particular routes, providing fine-grained control over middleware execution.

Kestrel is the lightweight, cross-platform web server that is used by default with ASP.NET Core. It's designed for high performance and is well-suited for hosting ASP.NET Core applications. Developers can also use it in combination with reverse proxy servers like Nginx or Apache for production deployments.

ASP.NET Core Identity provides user authentication, but it doesn't include OAuth as a standard provider. OAuth is a separate authorization framework that can be used with ASP.NET Core for scenarios like external logins, but it's not part of the Identity system.