The device will be available in 32 GB and 64 GB versions, both expandable via microSD up to 200 GB. However, a report from SamMobile claims that Samsung confirmed the US market will only be getting the 32 GB model of the S7. This could also be the case for certain markets in Europe.
The device will be available in gold, white, black and silver color, though their availability will vary from country to country.
If you purchase a carrier-branded device, it seems very likely that the device will be locked to the first SIM that you insert. This means that, if you want to switch carriers, you will have to contact your operator and ask them to unlock your device.