It's gossip that gets around, though. I've heard it before that the books took in Devlin and Emmerich's notes for sequels, but I've never seen the source myself. Same sort of gossip that ID4 is a Stargate sequel because of some of the similarities between the third book and ID4, I guess. Speaking of, I'm now onto Book 3 of my rereads! I try not to binge read series these days, so I always take breaks between series and franchises, and started Retribution last week. I'd forgot all about the Setim's defence system on Earth!
Probably not. It's so far removed from SG1.