Question on higher dimensions and gravity

Hi,

I read on this page:

Why exacly 11 dimensions? [Archive] - Physics Forums

that there are 11 dimensions because:

"A one dimensional matrix that describes EM. A two dimensional matrix that describes the weak force. A three dimensional matrix that describes the strong force. Now you are a theorist, and you see that gravity is described by a four dimensional matrix. So the logical thing to do is to lump all of these matrices together and get a 10 dimensional matrix. And you argue that the extra six dimensions that describe all of the forces are just tiny little dimensions so 1+2+3+4 = 10."

It goes on to say that:

"You have all of the forces in your 10 dimension matrix, but you don't have any matter..... Hmm.... it turns out that you can try to fix this problem by adding one more dimension which turns a force into matter and matter into forces. So this is where you get 11."

Here are my questions:

1. How accurate is this post? I could only find its information in one place.

2. How come we stop at a 4 dimensional matrix? If the forces were unified at the big bang, and they broke off from each other to get where we are today, couldn't they break off from each other even more, forming a need for an extra 5 dimensions?

3. I understand that gravitons are to gravitational waves as photons are to light waves. I also understand that Einsteins equations show that gravity is the curvature of space. However, when you think of "space" you are usually thinking of directions. Space isn't anything. "Space" is just directions. Einstein can show how gravity is the change of directions as two objects move in four dimensions, but is the actual reason gravity happens because of gravitons and gravitational waves, not the curvature of spacetime? For example, if the post I quoted above was correct, EM has photons that change an object's direction in one dimensional space, W and Z bosons change an object's direction in two dimensional space, gluons change an object's direction in three dimensional space, and gravitons simply change an object's direction in four dimensional space. That is why we have experimentally proven gravitational time dilation.

If anyone could answer any of these questions, that would be great!

Thanks,

Guymillion