17-55 or 24-70

I have a 550D with the kit lens 18-135 IS. My friend is selling some of his zooms (says he wants to go prime) and he is giving me good deals. Among the zooms he is selling, I am particularly interested in the 17-55 and the 24-70.

Yes both of them are 2.8 with a few differences such as the focal lengths, L, EF-S/EF mounts, IS etc. No matter, I can get either at very very good prices so money is not an issue (friendly prices :D).

Since I have just used my kit lens, I really do not know the difference between the two in terms of focal length; their reach, how wide, how far they can zoom etc. I've read lots of threads here and I still am confused. I use a crop body and here are my questions:

1) using the 24-70 at 24mm, let's say I focus on a car lengthwise with the car's front is at the left-most of the frame and the car's back at the right-most part of the frame. let's say I use a tripod so this "scene" or frame will stay put. will this "scene" or frame be the same if I switch/use the 17-55 zoomed at 24mm?
2) the 24-70 is equivalent to 38.4-112 on a crop body correct?
3) will the 17-55 have the same reach as 24-70 on my 550D?

4) what is (if there is at all) the FF focal length equivalent of the 17-55 in terms of focal length in a crop body?

Thanks in advance.

-wolv