I've been watching the trailers and stuff again, and I'm seriously tempted to go see this.
The stuff I've seen for the movie has gotten interested in the comics, are there any big must reads that would be a good place to start?
Difficult to say, you're talking about several decades of uninterrupted continuity (no magical reboots here!) so there's a metric ton of material out there. It's been my experience though, that while Dredd stories (especially the "epics") contain an awful lot of continuity and callbacks to previous stories, they tend to be written in a way that you don't *have* to have read those already.
Yeah, there was a running gag about Dredd liking tight boots and the reason he liked them tight that was explained over a 15 year period. If you had been reading all that period, it was a nice little easter egg.