Redmine

Hi,

I'm new to Redmine (and Ruby) I've been looking for a support system for my site and Redmine looks like it fits the bill. I have a question though, users have accounts on my site already is there a way to do the following:

a) Integreate redmine into the site so when they log on to my site they log into redmine.
b) A way to create accounts/delete accounts on redmine when someone registers/is deleted from my site.

Also is there an API?

I had a search around but didn't find anything in the wiki relating to this.

~Rowan