FTS with more than one language in body and with unknown query language?

Hi,

I have a text corpus which contains either German or English docs and
I expect queries where I don't know if it's German or English. So I'd
like e.g. that a query "forest" matches "forest" in body_en but also
"Wald" in body_de.

I created a table with attributes body_en and body_de (type "text"). I
will use ts_vector/ts_query on the fly (don't need yet an index
(attributes)).

* Can FTS handle this multilingual situation?
* How to setup a text search configuration which e.g. stems en and de words?
* Should I create a synonym dictionary which contains word
translations en-de instead of synonyms en-en?
* Any hints to related work where FTS has been used in a multilingual context?

:Stefan