Class templates in C++ provide the ability to create classes that can work with a variety of data types without the need to redefine the class for each type, offering a level of genericity and flexibility in code design.

The short int type in C++ is typically 16 bits in size. Given that it's signed, half of the 2^16 possible values are negative. The range thus typically starts at -32768 and goes up to 32767.

The diamond problem arises in C++ multiple inheritance when one class inherits from two classes that have a common base class. This can lead to ambiguity regarding which base class member should be accessed. The "virtual" keyword before the base class prevents the compiler from creating multiple instances of the base class, thus resolving the diamond problem.

The "Rule of Three" in C++ suggests that if a class requires a user-defined destructor, copy constructor, or assignment operator, it likely requires all three. This rule arises due to the intricacies of dynamic resource management (like memory allocation) in C++. Implementing or omitting one without the others can lead to unexpected behavior.

In C++, structs are typically used for lightweight user-defined data types. They default to public member access, making it easier to access the members directly without the need for getters and setters. Classes default to private access and are generally used when encapsulation is a primary concern.

In C++, both structs and classes can have member functions, inherit from others, and serve many of the same roles. The primary difference is the default access level (structs default to public; classes default to private). However, structs are conventionally used for simple data storage without associated behavior or methods.

In C++, an abstract class is defined by having at least one pure virtual function. This means the function is declared but not defined within the class, ensuring that derived classes must implement it.

Hierarchical Inheritance is when multiple derived classes inherit from a single base class. All the derived classes share the features of that one common base class. This kind of inheritance structure resembles a hierarchy or tree structure.

Encapsulation is a key concept in object-oriented programming where the data (members) and the functions (methods) that operate on this data are bundled together as a single unit known as a class.

In C++, the "base" keyword is not actually used. The correct way to access base class members is through the use of the base class name or the scope resolution operator. However, "base" is a term from C#.

While erase can remove elements from a vector, to efficiently remove all instances of a value, you'd first use remove to move those elements to the end and then use erase. This is known as the "erase-remove" idiom in C++.

Both struct and class in C++ can have member functions, data members, and can support inheritance. The primary difference is the default access level: members of a struct are public by default, whereas members of a class are private. Other functionalities between them are essentially identical.