If we substitute 2 into x it'll be:
For part a: you just need to find how far the vertex has been moved from the origin, or the point (0,0). As the vertex is at the point (2,-3), it has been translated right 2 horizontally and down 3 vertically.
For part b: you use the info found in part a to create the equation in the form of y=A(x-h)^2+k. In this case, A =1, so you can ignore it. The h value is the horizontal distance the vertex has been moved. Since it has been moved right 2, this part of the equation would be (x-2). I know it seems like it should be plus 2, but values in parentheses come out opposite. For the k value, find the vertical shift, which is down3, or -3.
Now that you have h and k, substitute them back into the equation.
Your final answer for part b is: y=(x-2)^2 -3.
The question is a bit ambiguous: you may mean

or

Anyway, in both cases, the domain of a function involving a square root is found by imposing the content of the root to be greateer than or equal to zero. So, in the first case you have

In the second case, you have
