Can Apples be Macerated before Pressing into Cider?
Maceration is a traditional step in French and English cider production, whereby the pomace (post-crushing pulpy residue) is left to sit for up to a full day (2-4 hours probably suffices). This allows beneficial enzyme action, and the exposure to oxygen should help reduce bitterness and astringency.

I'm not sure what adding sugar would do besides increasing the costs and complexity; are the apples not sweet enough already?

Reference: "The New Cider Maker's Handbook" by Claude Jolicoeur.