knitpicks needles are here.
they are my favorite ones, too. I also have a pair of size 0 by Inox.
When I was first learning the 2 circ method, it was recommended to use different color needles and/or different lengths. It helps to make sure you're using the correct 2 ends. Once you've done a few pairs, it's not so important that they be dif lengths/colors - it's not too difficult to make sure you're holding onto the same needle in both hands.
16" is OK if you're only making one sock at a time, but I prefer 2 socks at a time so I like 24" but also have some 29" (it's too long, but usable). Right now most of my needles size 0 - 1 - 2 are all 24". My size 3 are 24" and 29", but I don't use them too often anymore for socks.