Why does Samsung Kies say that my device does not support software upgrading via kies?
Fortunately there is no region-locking for phones, just carrier locking.

If your phone came with European firmware then you should probably stick with European firmware.  Ideally you'd be able to find something from your carrier even if it was re-packaged by someone for Odin.

As for your network settings, there are a couple possibilities.  You may need to supply the APN information, which you can usually find by doing a web search for "&lt;carrier&gt; apn" or similar.  You might also need to flash a different modem if the one you have is buggy or otherwise incompatible with your device/carrier.