In Go, the ':=' syntax is used for short variable declarations. With ':=', Go infers the type of the variable based on the assigned value. This allows for concise variable declaration without explicitly specifying the type.

Buffered channels in Go have a fixed size buffer, allowing a certain number of elements to be stored before blocking. On the other hand, unbuffered channels have no capacity for queuing elements, meaning that sends and receives on an unbuffered channel must synchronize immediately. Understanding this difference is crucial for managing communication and synchronization between goroutines efficiently.

The ampersand (&) operator in Go is used to retrieve the memory address of a variable. It's crucial for working with pointers and passing by reference.

In Go, the float64 data type is used to represent decimal numbers with floating-point precision. It offers a wider range and higher precision compared to float32. The float32 type is also available but is typically used when memory optimization is a concern.

In Go, the 'panic()' function is used to cause a runtime panic, which stops normal execution of the current goroutine and begins panicking. Unlike 'defer', 'panic()' cannot be deferred and is limited to the goroutine in which it is called.

In Go unit testing, 't.Error' and 't.Fatal' both are used to report test failures. However, 't.Error' allows the test to continue its execution after reporting the error, whereas 't.Fatal' stops the execution of the test immediately upon encountering the error. This subtle difference is crucial, especially when you want to continue testing after encountering an error ('t.Error') or halt further testing upon encountering a critical failure ('t.Fatal').

In Go, the net/http package is commonly used for implementing middleware in web applications. Middleware functions in Go are functions that process incoming HTTP requests before passing them on to the main request handler.

For handling different options provided by the user in a command-line tool implemented in Go, the switch control structure would be the most suitable choice. The switch statement allows you to evaluate multiple conditions based on the value of an expression and execute the corresponding block of code. This makes it ideal for parsing and handling command-line options efficiently. Unlike if-else statements, which can become cumbersome with multiple options, switch statements offer a cleaner and more concise syntax for managing various cases. Therefore, in this scenario, using switch ensures better readability and maintainability of the code.

JSON is the commonly used format for data interchange in Go due to its simplicity, readability, and widespread support across various programming languages and systems.

In Go templating, the "." (dot) operator is used to access data passed to the template. This data context allows templates to render dynamic content based on the provided data.