1. Not so much "balance" but more for the beer to clean up (removal of off flavors, etc).
2. It can, but you're better off bulk lagering for consistency across the whole batch.
3. The "general rule" for lagering (at least the one I try to follow) is lager 7 days for every 8 gravity points of OG after initial fermentation. For example, at 1.056 = 49 days of lagering.