Ideally: no.

All new shiny new features shouldn't have waited for the (N+1).0 version, they should already have been part of the (N).(M) version.

In practice, the removing the deprecated cruft will remove blockers for some new features, but that should be rare.

Yes, the features don't need to be added immediately.

Good question. I guess sometimes stuff becomes unnecessary due to external factors and not due to new features.