Why would I use Joomla? - Joomla! Forum - community, help and support

hello,

i new joomla. questions due ignorance of functionality of joomla hope able answer them.

i idea od joomla's extensibility but:
1. joomla has it's own database. possible joomla use other database tables?
2. have begun working on tools developed in adobe flex , ruby on rails communicate own repositories. possible have use joomla? how these tools , joomla communicate , pass information? xml?
3. how joomla used in web services type of architecture?

i hope these questions not obvious.

cheers, phil.