If you are just importing content from another CMS I would write a scheduled job in EPiServer:
http://world.episerver.com/code/dannymurphy/Stoppable-Scheduled-Job-with-feedback/
That job then uses the standard IContentRepository to create content:
http://world.episerver.com/documentation/Items/Developers-Guide/EPiServer-CMS/8/Content/Persisting-IContent-instances/
That way you can run it whenever you want and have access to EPiServers complete API. Also you can see progress of the import through the job status.
In the job you can read the content as a file in any format you like or directly from the source CMS database or some xml or RSS feed perhaps.
I have moved content from PHP, Java and .NET CMS this way. In .NET you could even access the source CMS via WCF or SOAP if available.
The ServiceApi is relatively new and more focused on Commerce products and media assets rather than CMS page and block content so I wouldn't use that.
There is complete documentation below for the ServiceApi by the way, did you not find it?
http://world.episerver.com/documentation/Items/EPiServer-Service-API/
Regarding language management you can read more in the below links:
http://cjsharp.com/blog/2013/04/11/working-with-localization-and-language-branches-in-episerver-7-mvc/
http://tedgustaf.com/blog/2010/5/create-a-new-page-language-branch-programmatically-in-episerver/
Basically you have two options for multiple languages. If the content is just straight translations you should create nine different language versions (branches) of the same page. You can also have multiple sites in an EPiServer installation but that requires 9 separate licenses (and the associated costs).