First time SCROG,need some basic help

Hello
So im planning to scrog,I have my screen made and its 6x4 ft size,3.5in holes,have 10BB seeds,400+600w hps,will veg under 400w and switch to both for flower,need some basic help from someone who scroged before,I was thinking :
1.How many plants to scrog under? I was thinking about 8.
2.Is this screen enough? I was thinking about raising corners to the top so corners get more light and I win few inches space too..But as I read from tutorials like this one :
http://forum.grasscity.com/plant-training/48363-scrog-method.html
So as he says for scrog and 1000w hps 4.4ft x 4.5ft is perfect,so should I raise the corners up and go with some more space and light on sides or just do it simply like the way it is and dont bother myself for a first grow?
3.About how many toppings I should go for on each plant? Or dont top at all?
Thank you,really,everything would be helpfull,its my first scrog so you know im all cautious like with a little baby in my hands haha.

Here is a pic of my scrog. About 5 ft on the x axis and 3.5 on the y. Three plants. Low stressed trained them (no topping) into the netting. Once they had--during the veg stage--reached the planar coverage that I wanted, I went to 12/12 and the bud sites have grown straight up, adding a dimension of depth. 8 seems like a lot. Maybe that would be a hybrid SCROG and SOG? Don't know and don't have much experience beyond this only grow, that I haven't even completed.

The experienced guys on this forum ought to get a kick out of this: The Noobs leading the Noobs.