@dasuew - You’re welcome. Just to clarify, I’m a customer / Kickstarter backer of SmartThings, but I don’t work for them. My info comes from these forums and elsewhere, but I don’t speak for them.
Whilst you could buy a US hub and use US Z-wave devices, there are some considerations you need to be aware of:
The US hub will not have a European CE certification. My understanding
is that, amongst other things, the European standards are stricter than the
US FCC standards when it comes to max. transmission power and duty
German customs have, including very recently, been very strict in
disallowing the import, including via mail/courier, of non-CE certified
electronics. They have actually held parcels until the recipient has
provided documentary evidence of such certification.
Many US Z-wave devices for operating mains power equipment
(switches, dimmers, etc.) will only be rated for US mains voltages
You are also correct that European Z-wave devices will not work with a US hub.
The connection between the hub and the router is just a standard Ethernet UTP interface, so that bit will work fine