>> Let say we start with english website, but decide to switch to german at some point in time?
Press "edit" on the language, and edit url mappings, setting "en" for English, and "" to German will do it
>> In System perspective Language > Set as default. Is for editing I presume, so each newly added page is in default language?
It has 2 effects.
1) First, when you're logged in to console, that language will be selected by default.
2) Unless there other settings (f.e. host name bindings) when you access the website only by a host name, there will be a redirect to the first root page that belongs to the default language
>> Url configuration might help for case 1. or?
Yes, it will help. With it you can have urls like:
http://ip/ <- for German
http://ip/en/ <- for English
>> How can I get Url configuration in System perspective? I could not find it in packages...
It's available from v2.1.3, I'll sync the sources to Codeplex today or tomorrow. Upgrade procedure will also be available.
Note that that won't be a recommended release and it not yet support the c1contrib functionality.