I think their older stuff was more brutal. They've mellowed out a bit on Ire Works. Calculating Infinity is widely argued to be their best album. The music truly is math metal, and trying to comprehend what exactly is going on is as difficult as, well, calculating infinity. They also did a really sick EP with Mike Patton while they were between singers called Irony is a Dead Scene.
Not that I know of? As far as I know they're fine with each other... Dillinger does tend to feud with some people though, like Avenged Sevenfold. They hate those guys, haha. I'm pretty sure DEP and Converge are cool with each other. I found this article about Converge and DEP that you might find worthwhile: