The "API" template in ASP.NET Core is specifically designed to configure a project for building web applications that primarily expose web APIs. This template sets up the project with minimal middleware and settings for handling HTTP requests and responses, making it suitable for building RESTful APIs.

Integration tests focus on testing the interactions and collaborations between different units or components within a system. These tests ensure that the integrated parts work correctly together.

The role of the wwwroot directory in an ASP.NET Core application is to host static web assets, such as HTML files, images, JavaScript files, and CSS stylesheets. These assets are meant to be directly accessible by clients (e.g., web browsers) without going through server-side code. Placing static files in the wwwroot folder ensures they can be served efficiently and improves the performance of the web application.

In this scenario, the most suitable approach is "Database-First." This approach involves generating data models based on an existing database schema. Entity Framework Core provides tools like scaffolding to create models from an existing database, making it easier to work with legacy databases in your ASP.NET Core project.

The feature that would help you accomplish this is ASP.NET Core Identity. Identity is a membership system that enables you to add authentication and authorization features to your application, including user account management. It provides features like user registration and login.

NUnit is a popular unit testing framework for .NET applications, including ASP.NET Core. It provides a robust and flexible way to write and execute unit tests, making it a common choice for ASP.NET Core developers.

The primary purpose of the IExceptionHandlerPathFeature interface in ASP.NET Core is to provide access to the details of the exception that occurred during the request processing pipeline. Developers can use this interface to capture information about the exception, such as its type, message, and stack trace, for custom error handling or logging purposes.

The .NET SDK (Software Development Kit) plays a crucial role in ASP.NET Core development by providing the tools necessary for building and compiling ASP.NET Core applications. It includes the command-line interface (CLI) tools like 'dotnet' for project management, building, and running applications. Debugging, database management, and web server request handling are tasks typically handled by other components of the development stack.

In an ASP.NET Core application, it's not secure to expose sensitive information like a production database connection string in appsettings.json. To securely manage it, you should store it in an environment variable. This approach helps protect sensitive data from accidental exposure and is a best practice for configuration management in production environments.

In an ASP.NET Core project, the .csproj (C# project) file is crucial for specifying the SDK version, dependencies, and various project-related configurations. It serves as the project file that orchestrates the build process and defines the project structure.