What do explicitly-defaulted constructors do?

Consider the following:

template <class T>
struct myclass
{
    using value_type = T;
    constexpr myclass() = default;
    constexpr myclass(const myclass& other) = default;
    constexpr myclass(const myclass&& other) = default;
    T value;
};

• To what constructor bodies these function are equivalent?
• Does myclass<int> x; initialize the integer at 0?
• For myclass<std::vector<int>> x; what does the default move constructor do? Does it call the move constructor of the vector?