As for features on the SB-600 the head cannot rotate, which means limited positions and that was a feature I wanted so as soon as I seen that in the specs it was a no no, then you get to the more expensive models.
I'd rather stick to the cheaper budget end myself as I am new and no pro, I don't really need the best of the best, after all I have no plans to make any money out of it, it's more a hobby for me, but it's your money and like you say the i-TTL is going to be more useful for you, my plans are some macro stuff probably using 2 flash guns, didn't really want to be paying £500 for some lighting you see.
Yes the triggers will work like that no problem, pressing the shutter and firing the flash from the triggers, my explanation was more for my plans of using the trigger off camera as to avoid any movement when taking shots(macro, when I get round to it), there are very versatile in there use being transceivers, they can send and receive.
Don't count out the 568 with needing a trigger, if it's on camera obviously it don't, also you have S1 and S2 modes, which mean they will fire when they see another flash fire, like my second picture the flash has seen my little flash from my compact and fired, something I forgot to mention
so you can use your in built flash on your camera as a trigger, no need for triggers like that, although then there is no i-TTL, unless you get Yongnuo newest triggers that pass on the i-TTL for nikon, they have just been released
http://www.ebay.co.uk/itm/281108042059?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 just to complicate things more
Depends how serious you think you will get into it, the bug can bite very hard, I am just trying to balance the kit out what I buy, I don't want to throw too much money at it only to then not get any use from it.
No need to thank me, I enjoy a discussion on all techy stuff, it's another part of this I like.