The “Archive Editions” line was discontinued in 2014. It’s since been replaced by DC’s “Golden Age,” “Silver Age,” and “Bronze Age” Omnibus editions.
Nope! Red Jack is only really featured in one Doom Patrol story arc, and Mr. Nobody is just too weird to really interface with the rest of the DC Universe… but the Doom Patrol has always kind of existed in their own corner of continuity, Beast Boy being the rare social butterfly among them.
The most crossover you’re going to see with the Doom Patrol stable of villains is the Brotherhood of Evil, who have followed Beast Boy to menace the Teen Titans from time to time – as well as a nascent Justice League, in JLA: Year One.