on a FF, 17-40 is a little wide for most people's general-purpose, walk-around lens. It works out fine for some people, but I think they tend to be crop body users. What about a 24-105 and a 70-200? I know there's some range overlap, but the 24-105 will give you IS, same max aperture, get you a reasonably wide angle, and cover the rest of the general purpose range. It's a bit more expensive than the 17-40, but at realistic street prices, not that much more expensive. ($845 on Amazon via a marketplace seller).
I think that kind of answered questions 1 and 2, but to directly answer your questions...
1) There are loads of options, I think you've got two good options, and the only other combo I'd recommend is the 24-105 + 70-200.
2) The 17-40 is great for some people, fine for others, and not long enough for still others. For landscapes, it'd be great. For pictures of your daughter, 40 is still wide enough to emphasize the center of the frame over the edges, which introduces a very distinctive perspective. Unless you shoot in very low light, my gut feeling is that you wouldn't miss IS that much, especially because with the 6D you'll be able to ramp your ISO up much higher than you're used to.
3) I love my 70-200. It's very usable for portraits- can get a bit tight indoors, though. For outdoor portraits, or larger indoor spaces, it's a lovely lens. Then again, I have a 7D, so I'm dealing with the crop factor... my guess is on a 6D, it would be fantastic.
4) Canon has extended the rebates the past couple times they have been set to expire. Will they extend them again? No one knows but their marketing department. Will vendors like B&H continue to offer below-MAP "add to cart" prices, effectively rendering the rebates extended? Again, unclear. If you want to be safe, now is a very good time to buy.
Just my two cents...