1&2, I have a Dahua 2100c bullet and when I tried to setup FTP, my cam got totally fckup and web-interface didn't started after the setup at all!. Had to do full reset on camera side.
3. You can try http://ip-address:9988/onvif/media_service/snapshot
well you get what you probably expect these chinese, cheap but not perfect quality
Dahua is doing some development on ONVIF side and that's probably the reason why there are some undocumented features like that snapshot, also it has telnet open and hard coded root password so I wouldn't put my cam on unsecure network!
btw, where did you bought your cam? From Finland?
heippa!