strings,pointers, and using namespace std;...................?

what does this mean?

using namespace std;

and I don't have a referance right now, but which one is declaring a string?

char* cString = "hello!";

//or

char *cString = "hello!";

I Know what pointers are, I just forgot which was which....

and when you use an array of chars, like this

chr cString[6] = "hello!";

//it can only hold a max of 7

chr cString[] = "hello!";

//I didnt specify what size the array was
//but it can only hold 7 now because thats what I
//assigned to it

//if i use the method above(char * .... etc)
//will I be able to change the length(make it longer) 
//after the first time I change it?

//and finally

//how do I redim an array?

Thanks.......