There's documentation about how to get that setup with N1 here: https://github.com/nylas/N1/blob/master/CONTRIBUTING.md
There's much more on the Sync Engine page here: https://github.com/nylas/sync-engine
Why is that a big deal? I've worked with IMAP, and it's not that bad.
I don't believe you.
Every email account provider is different in horrible, horrible ways.