User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-4823600-20130209134048/@comment-115.133.206.134-20130209142005

1. I think the author mention before that it was a "special" for the epilogue of The Heroic Oppai Dragon Arc.

2. No Rias just simply didn't realize that it was her brother, sister-in-law and the other Satans. P.s. but it is hinted that Sirzechs and Grayfia did the same thing as Rias and Issei before.

3. Not all since only Rias and Akeno has been scattering the Dragon powers for Issei.

4. Who knows maybe after he gains a sub-species Balance Breaker.

About the anime who knows maybe they might create 1-cour for three seasons then 2-cour for season 4 and above.