1) install (trough adept, for example) the language packages for your language (i18n? kde-lang-something?), that ought to help.
2) No, it should be easy, but you can just as well use ifconfig (wired) or iwconfig (wireless, non-secured or WEP) or wpa_supplicant (WPA/WEP/wireless/wired) or any of the other tools around. Not sure how KDE handles it nowadays, but typically all you do is configure an interface and bring it up, and if you use DHCP (don't manually set ip addresses etc., but get them from a dhcp server), run dhclient or dhcpcd for the interface - the graphical desktop tools usually do just this.
I'm pretty sure Adept (apt-get) works by using URLs like other apps do, not plain ip addresses, so if it works that would imply your network connection is fine - but if you can't browse any sites, that sounds interesting. Does pinging work?