I'm confirming this from the other czech source. The US 3G Kindle works in Czech republic the same way as it works in the US, except the 3G signal is restricted to 3 large cities. You can't download unsupported ?and large? files + you pay for conversion through your @kindle.com address when on 3G. No additional charges apply.
So my last question
Is there only one type of Kindle 3G+Wifi on sale in retail stores (as Staples or BB) which works globally, or are they selling US only type and one for global use.