Can someone suggest any good resources to learn about how various integer data types are manipulated in C++ from a competitive programming perspective ? I'm having problems with understanding them, for example

• When you do something like long int x = y*z, where y and z are long long int, but the value of y and z are small (say 100), would it cause overflow ?

• When you do something like int x = (a*b) % prime when a, b, prime are of the order 10⁹ (but still stored in int), would it cause overflow ?

• What is the difference between double/point/long double etc ? How they're manipulated (like the above) ?

• Does using longer (for example, using long long int instead of int) causes the programme to run slower ? If yes, then how much (like a factor of 2 ? a factor of 4 ?)

• Why almost nobody uses long double in competitive programming ?

• When manipulating digits of HUGE orders (like 10⁵⁰⁰), how that's done in CP ?

• Why the strange result in running the following code ?

#include<iostream>
using namespace std;
typedef unsigned long long int ll;
int main(){
    ll x = (1<<30), y = (1<<31), z = 2*x;
    cout<<x<<" "<<y<<" "<<z<<'\n'; //why y is not equal to z ??
    return 0;
}