The ASCII value for the uppercase letter 'A' is 65 in decimal. ASCII (American Standard Code for Information Interchange) assigns each character a unique number between 0 and 127.

The break statement is primarily used to terminate loops and switch statements. Using a break outside these constructs, like directly inside a function without a loop or switch, would result in a compilation error as it wouldn't have a clear context to operate within.

The ~ operator is the bitwise NOT operator in C++. It inverts each bit of a number, changing 1s to 0s and 0s to 1s. & is the bitwise AND, | is the bitwise OR, and ^ is the bitwise XOR operator.

In C++, the "std" stands for the standard namespace. A namespace is a declarative region that provides a scope to the identifiers inside it. Using the "std" namespace, we can access features of the C++ Standard Library without prepending their names with std:: each time.

The goto statement in C++ provides an unconditional jump from the goto to a labeled statement found elsewhere in the code. Although it allows for more flexibility in controlling the flow, its overuse or misuse can make the code less readable and more prone to errors. The modern programming paradigm usually discourages its use.

In C++, to declare a function that returns an integer, the correct syntax is "int functionName()". The type "int" signifies that the function's return type is an integer, and the parentheses "()" indicate it's a function declaration. Actual implementation or body of the function would follow the declaration.

In C++11's range-based for loop, the const keyword ensures that elements are not modified, effectively preventing unintentional copies or modifications to the elements.

The loop while(true) will continue to execute indefinitely since the condition is always true. This can potentially lead to an infinite loop, consuming CPU resources, and making the program unresponsive unless externally interrupted.

When a class is frequently copied or assigned, it's crucial to consider the efficiency of these operations. Move semantics, introduced in C++11, allow resources to be "moved" from one object to another, without making a copy. This can greatly improve performance. Shallow copy can lead to issues like double deletion, and avoiding constructors or only using private members doesn't address the efficiency of copying or assignment.

Abstraction in C++ refers to the concept of hiding the complicated reality of an object while only exposing operations relevant for that object. This allows for simplifying complex systems by breaking them down into smaller, more manageable parts, enabling developers to focus on high-level functionalities.