Understanding char array[] and string

I am new to programming world. Now I am learning C as my first programming language. I found something strange to understand.

I have learned in C we can represent a String as a sequence of character like this (using char array)-

char status[10] = "Married";   

I have learned that the problem of this approach is - we have to tell the size of the status array during compilation.

But now I have learned we can use a char pointer to denote an string like -

char status[10] = "Married";
char *strPtr;
strPtr = status;

I did not understand it properly. My questions are -

1. How can I get char at index 4 (that is i in Married) using the strPtr?

2. In status there is a null character (\0) at the end of the string represented by the char array - M->a->r->r->i->e-d->\0. So by using the null character (\0) we can understand the end of the string. When we use strPtr How can we understand the end of the string?

Thanks in Advance.