The holes were already drilled in my bus when I went to fit mine. They work perfectly and from what instructions I have read they are correctly done.
So, the brackets need to be fitted just off of vertical as in pictures 1 and 3. Definitely not as vertical as in 2 or as laid back as in 4, 5 & 6.
This is for both A and B post brackets (though obviously mirrored on the B post...)
Height wise, you need to just clear the top of the seat backs. Go too high and the canvas goes baggy (due to the rake of the A post).
One final thing - if you have the new type brackets that have an offset bulge to receive the tangs on the poles then the wider part of the bulge goes at the bottom.
Good luck!