Medusa, the name is the Britt Ursula. I can check my receipt for the specific number.
Here are the NY numbers:
Soho store (where I got mine and they had a few others): 212.941.1511
Prince street: 212.533.8930
Midtown: 212.459.9863
Broadway: 212.579.2587
Columbus Ave: 212.724.4076
Third Ave: 212.355.2949
Fifth ave (I would try them last--they were completely sold out but maybe someone made a return): 212.352.0936
As for size, it seems like almost everyone that tried these were in between sizes. I would get your usual size and a size up and just return the one that doesn't fit. I think I could really have gone either way, but I ended up with the smaller size because I could not find a 4. If you are more pear-shaped or have fuller hips, I think you're more likely to size up.