As to his Marxism, I think that the movie Straight To Hell came about from some Marxist protest (concert?) that fell apart and so the gathered celebs and Alex Cox decided to make a movie quickly. Some of this backstory is in the documentary that is on the DVD.
Lately I've been really enjoying the last Strummer album a lot. Took a few listens, but now it holds a steady place in my car CD changer. The version of Marley's "Redemption Song" is just heartbreaking. You were lucky to meet him. I've talked to a few people who did, and all of them talked about what a nice guy he was. As for "Straight to Hell," you must be a glutton for punishment if you own the DVD. Yeesh.