eek! I would be afraid to shoot at 1600 with a flash.
and that's why it didn't work for you. that is how it's done. you can get away with 800 and 400 can work if you want ot push the flash.
yes she is shooting the 24-70. no you don't need to upgrade, the flash has enough juice.
dave fec should be realtive to the subject. -2/3 on a dark subject will give you an overexposed shot, not fill. what's more fill does not add dimension, it removes it. if you are creating dimension with your flash the flash is now your main, ambient is fill.


