Re: Ignoring Superman 3 and 4
I think he did what he did because he's primarily a fan of the Donner films or at least parts of them but he also knew that to tell the kind of story he did it can be even better to have a Superman that the audience has a bit of familiarity with. It's the same reason that the Batman vs Superman script did things it did so that it could be a vague continuation of the previous film batman and to a lesser extent a previous Superman. It could have worked well with new versions of a batman and superman but it couldve worked even better with versions of the character whose history we had already invested in.
I didn't really mind want Singer did. I liked SR a lot but it had more fundamtal problems than just continuity as far as getting a bigger audience.
As far as the audience and the timeline and dates I always saw Singers reasoning as the film being on a sliding timescale like the comics or the Bond films. More so since its not even a direct sequel.