So, let's say I want to do some indoor studio portrait photography and the setup I want to do is this.

Nikon D90 set in wireless commander mode (just learned how to set this up with my SB 600 flashgun)

2 flashguns (one SB 600, the other, i'm not sure yet because I haven't bought, either looking at a used 2nd Sb600 or a used SB800 as another Master/Slave unit)

rear illuminating constant illumaniting non strobe light for the back or side of the side

so both flash guns will be off to the side, either directly illuminating the subject from each side or bouncing off umbrella diffusers, or directly thru softbox reflectors.

Now if I use D90 + 2 x SB600 slaves, according to the manual I have to activate the camera's popup flash to trigger the wireless SB600 slaves (actually I dont even know if I can trigger TWO slaves off the same channel but I assume I can) and I dont want to use the forward flash so I'll have to find some way to obscure it, (and I tried blocking with my hand and it still triggered the 1 slave I have so I know its good)

Now if I use the D90 + 1 x SB600 and 1x SB800 master unit both off camera, will I still have to popup the in camera flash to trigger the master SB800 unit which will then trigger the SB600 slave unit?

If so, in order to not use the popup flash will I have to resort to using a pocket wizards setup to trigger without using the popup flash. I'm thinking of pocket wizards anyway because I have the wireless card in my Sekonic lightmeter to remote trigger the flashes for lightmetering

iirc, the popup flash will not affect exposure when used to trigger ocf as slaves. and yes, you can trigger 2 slaves off the same channel.

i believe covering the pop up defeats the whole purpose of i-ttl. the pre-flash measures exposure and then sends the slaves teh appropriate flash power. i could be wrong but i believe thats how the system works.