When calling a function with default arguments, the provided arguments are matched from left to right. If you provide fewer arguments, the remaining ones are matched with their corresponding default values, if any.

Steve should use an enum (enumeration) in C++ to achieve this. An enum is a user-defined data type that consists of a set of named integer constants. In this case, he can create an enum with values RED, GREEN, and BLUE, ensuring that the variable can only have one of these predefined values.

Inline functions should primarily be used for functions that are frequently called. The decision to mark a function as inline should be based on how often it's called, as inlining is most beneficial when used with functions that are called frequently to reduce the function call overhead.

Lisa can use Default Arguments in C++ to modify her function. By assigning a default value to one of the function's parameters, she can make it so that if only one argument is provided, it calculates the area of a square by using the default value as the second argument.

Emily should use a "For Loop" to calculate the factorial of a number. A "For Loop" is well-suited for tasks that involve iterating a specific number of times, such as calculating the factorial of a number, where she can easily control the loop's start, end, and iteration conditions. She can iterate through the numbers from 1 to the given number, multiplying them together to calculate the factorial.

Anna should use the "If-Else" statement for this task. It allows her to evaluate a condition (in this case, whether the number is positive, negative, or zero) and execute different code blocks based on the result.

Lucy should provide a function declaration. A function declaration defines the function's name, return type, and parameter list without specifying the actual implementation or logic. This allows her to declare the function's existence and signature without writing the code for adding two numbers.

When an inline function is called inside a loop, the function is executed for each iteration of the loop. This can potentially lead to code bloat if the function is large, but it can also result in better performance as there is no function call overhead.

Function overloading primarily focuses on the function's parameter list, allowing you to have multiple functions with the same name but varying parameter types or numbers. The return type is not considered when distinguishing between overloaded functions.

The concept where the function's return type is deduced from its return statements in C++11 is called 'auto.' Using 'auto' for return types allows C++ to automatically deduce the type based on the return statement's expression. It's a powerful feature that simplifies code and improves readability.