List iterator vs. vector iterator

I have two questions regarding iterators.

1. I thought the once you define an iterator to an STL container such as a vector or a list, if you add elements to the containers then these iterators won't be able to access them. But the following code defines a list of five elements and then adds another element in each loop iteration and results in an infinite loop:

   #include <iostream>
   #include <list>
   
   using namespace std;
   
   int main()
   {
       list<int> ls;
   
       for(int i = 0; i < 5; i++)
       {
           ls.push_back(i);
       }
   
       int idx = 0;
   
       for(list<int>::iterator iter = ls.begin(); iter != ls.end(); iter++)
       {
           cout << "idx: " << idx << ", *iter: " << *iter << endl;
           ls.push_back(7);
           idx++;
       }
   }
   

   However, doing the same for a vector results in an error:

   #include <iostream>
   #include <vector>
   
   using namespace std;
   
   int main()
   {
       vector<int> vec;
   
       for(int i = 0; i < 5; i++)
       {
           vec.push_back(i);
       }
   
       int idx = 0;
   
       for(vector<int>::iterator iter = vec.begin(); iter != vec.end(); iter++)
       {
           cout << "idx: " << idx << ", *iter: " << *iter << endl;
           vec.push_back(7);
           idx++;
       }
   }
   

2. I thought that when the vector container must be resized, it does so at powers of 2 and is located to a new area of memory, which is why you shouldn't define an iterator to a vector if you adding elements to it (since the iterators don't get passed to the new memory location). For example, I thought a vector containing 16 elements, after calling the push_back function, will be allocated space for 32 elements and the entire vector will be relocated. However, the this didn't happen for the following code. Was I just mistaken?

   #include <iostream>
   #include <vector>
   
   using namespace std;
   
   int main()
   {
       vector<int> vec;
   
       for(int i = 0; i < 4; i++)
       {
           vec.push_back(i);
           cout << "address of vec: " << &vec << ", capacity: " << vec.capacity() << endl;
       }
   
   
   
       for(int i = 0; i < 20; i++)
       {
           vec.push_back(i);
           cout << "address of vec: " << &vec << ", capacity: " << vec.capacity() << endl;
       }
   }