Actually, I'd sell the 18-55 and get the 18-105. ;-)
Depending upon your venue (outside? inside?), you might find that lens would satisfy most of your needs.
As for your list, I tend to use both the 35 and 50 a lot. I have them both in 1.8, and _rarely_ would I _ever_ shoot more open than that - too much would be far out of focus. If you're shooting people, you will likely want to maintain some focus in their faces and bodies, even when shooting shallow DOF.
I have, on occasion thought that extra 1/3, 2/3 stop would matter, but I don't think I have missed it. There is something to say for the bokeh, but the savings also talk.
Frankly, I would certainly would recommend saving the extra money and go for an f1.8 (on a side note - and the opposite side of my recommendation, the wider aperture would be a somewhat faster focusing lens, and a brighter viewfinder for the money you'd spend - that's you _real_, not imagined advantage).
For a portrait lens, I'd opt for the 50mm 1.8; if you're outside, the 18-105 or 18-55 will likely cover most of your shots.
You'll need a lot of flash; two SB900s should be on your plate, which is more than the lenses you're looking at. ;-)