Can you have many adjacent windows along the perimeter of the top of a wall?
This answer is pretty much the same as Jasens, I elaborated a little bit.
Each post, at the corners and between the windows are supporting a rafter, sized properly for the roof load. Set between those rafters are purlins which make up the rest of the support for the roofing. The roofing is attached to the purlins.

So to answer you first question, as long as you follow this post and rafter example, you could have as many as you prefer as long as you have enough wall space for racking resistance. 

In other words, don't make the windows too tall.

I added a pic to show what is going on with the roof.