>I understood the SB-24 and the SB-400 had limitations, does >that also mean they would not work if I had PWIIIs? Just >curious.
The SB-24 can be triggered by PW Plus III transcievers, though you will have to adjust the power level at the Speedlight. The SB-400 was designed to be used on camera or attached to the camera hotshoe via a TTL extension cord. There is no way to control the power level and I suspect it can't even be triggered off camera with a PW Plus III.
>Why would I use the SB800 as a trigger and not the D700?
The SB-800, SB-900, and SB-910 can control up to three remote groups. If you place the diffuser dome on and aim the head vertically it can trigger speedlights behind the camera where the D700's built in Speedlight won't be able to. The built in Speedlight like the SB-700 can only control a maximum of two remote groups.
>Also, would this set up let me adjust the output of the SB600s >from the camera?
Yes! With the remote Speedlights set in remote mode and the built in or on camera flash set in Commander mode. This allows you to use either Manual flash control (set the power level of each remote group) or i-TTL flash control (setting the flash exposure compensation of each remote group). Good Luck and Enjoy your Nikons!