Anybody worked with any multi-language installations?
Any lessons learnt?
Anything that we need to take "extra" care of?
Any experiences with multi-language self service?

Techie gurus, any pointers on the coding style we need to be careful about??

Coding-wise, be aware of any tables that have translation-table equivalents - these end in _TL.

Essentially you will need a restriction on the _TL table, along the lines of:

...
AND x.LANGUAGE = USERENV('LANG')
...

Usually (but not always) there is a view of the base table joined with the _TL equivalent and incorporating this restriction; that will end in _VL