Problem when changing phpbb version

I'm a noob and I noticed that changing from phpbb2 to phpbb3 can mess up my phpbb2 theme (darkages). Is there someting I can do to correct this easily?
By the way I report an error in the theme: the color of text in quotes is wrong and must be corrected manually (at least that's what I had to do).
Also, which version of phpbb3 do you use (the Gold or some Release Candidate)? If you upgrade to a new version, does my forum get automatically updated?

Thank you very much for your replies.

phpBB2 => phpBB3:
That's normal since the theme's not adapted for phpBB3

Automatic updates?:
When we upadte, every forum on every server is updated

phpBB3 Gold?:
Not yet, wokring on it

Caihlem