If you have the movie, then just use handbrake to rip the DVD to mp4. It's a pretty straight forward process. I'm sure there have been plenty of threads on it in this forum, so just to a quick search.
Yup. I ripped Iron Man and Iron Man 2 to MP4 and had them on my EVO but never had 1.5-2hrs of free time to watch them. There are lots of converters out there but handbrake is free. Just use the iphone settings and it will work fine for the EVO.