Re: Omnibus help
For someone just dipping their toe back into superhero comics, Gotham Central is probably the best choice. It's a procedural, like many of the shows on TV these days, and the focus is on ordinary people trying to cope with the insanity of life in a metahuman universe. The serial storytelling is better suited to binge-reading than most Silver Age tales, which are pretty repetitive (and aimed at younger readers to boot.) It's also very well-written and illustrated.
If the Doom Patrol omnibus collects Grant Morrison's run - well, it's a very well-regarded series and one of my old favorites. It was The Matrix before The Matrix was, only with extradimensional bugs instead of rogue AIs and a hell of a lot more drugs. Great stuff at the time, but I don't know how well it holds up these days, especially to a new reader.