Why did he give them the coordinates to NASA?

Because he realized that they needed the coordinates because that is what would lead them to discovering NASA, getting the necessary data, and saving the world.

How did he ever find NASA the first time?

That's the point of a paradox. It doesn't have a beginning or an end. It has to loop endlessly in both directions.

Can someone explain to me 5 dimensions of space?

Oh boy.

Imagine a point in space. It has no surface area, no volume, nothing. It is infinitely small. This is zero dimensions.

Imagine a line. It has an infinite length, but has zero width and height. You may also imagine a point that can only be able to move forward or backward. This is one dimension.

Imagine two lines. One line is infinitely long, and the other is infinitely wide. Now, our point can travel forward, backward, left, and right. This is two dimensions. For this two dimensional plane, you can picture it as a graph. One line is the x axis, the other is the y axis.

Imagine three lines. A line is infinitely long, one is infinitely wide, and the other is infinitely tall. Now the point can move forward, backward, left, right, up, and down. The infinitely tall one is now our z-axis on the graph.

Now, imagine four lines. It's the same principle as the others. The point can now move in two extra directions within the fourth dimension. These are known as ana and kata. To go through the wormhole, their ship had to travel in one of those directions to go through it.

The same applies for the fifth.

Once you have "the equation" can you just manipulate it? Or is it understood that we just in general not understand it but "they" do in the future.

We, as the audience, aren't supposed to know exactly what "the equation" is or how it works. However, I believe the scientists in the film do, and are working to achieve the abilities of "them"