phpbb3 styles version upgrade

Hello everyone. I am putting up a forum using Phpbb3 and I uploaded DarkFantasy template. After installing I had problems with the way it was responding. Come to find out, that Template was a 3.0.2 and I looked into getting it to fit the Phpbb3.0.3 program and I was told that it could be
but it might eventually screw my forum up in the future with bugs. So I wanted to know if this is true and or should I just stay with the Templates that are available for the Phpbb3.0.3 program that is now available?

Also,.. I am now looking at the Acid Tech Lime Template and I would like to know how to take the triangle out of the middle of the header panel and instatall another picture but I want to keep the color bursts on the right and left of the header, is this possible?

thank you for your time and effort
-Robby

If you liked a style and it is for phpbb3.0.2 , you can upgrade it for new version phpbb3.0.3