Alright, I finally read it and it was awesome. That appeared to be the evil Quasar, correct? What I want to know is where does this continue? I wasn't planning on reading the Inhumans and the Imperial Guard Realm of Kings. I didn't read the War of Kings either, just the Guardians stuff. Did I just get sucked into a big crossover story arc? I really want to continue this.
Thanos was shown to have the Reality gem in the Cosmic Powers Unlimited series (issue #1) when he summoned Captain Mar-Vell. I'm pretty sure he never used it in the Infinity Watch series. He brought it out during the Infinity War, but it was a fake to trick the Magus.
castleking answered the Infinity Gauntlet question very well.