Ishibumi's comments after were that he's trembling at the opportunity to write this, since he's wanted to do it for over 5 years now.
As for Shin which will get its synopsis in a few days, volume 1 indeed will be an Issei volume. Since it's volume 1, he thinks that there will be some new people picking it up, thus all characters will be introduced, the setting, and the view of the world at this point in the story. It will be a hopping on point for new readers, and an official refresher for current readers or ones catching up.
For people who have stuck with the series from the beginning, Shin volume 1 will have some sentimental value, as it will compare and contrast with volume 1 of the original. Issei has 29 full volumes (counting side stories) of content behind him now, is the strongest Sekiryuutei in history, and is now the high ranking devil, so he feels a bit troubled by starting a series of like this. How will readers feel about Issei having started as a scrawny kid who couldn't even control magic?
Slashdog volume 3 will come a bit later than Shin volume 1.
About Hero, the 3 remaining episodes will be the rating game. He emphasizes that besides from the finale, that what's about to happen with Gasper truly is a treat for novel fans, and urges them to tune in to it. Hades, Diehauser, and Rudiger have all appeared finally, but him and the staff couldn't think of a way to show Zeus and Poseidon appear without breaking the pace so he apologizes for that.
AND FINALLY, A HUGE TEASE:>...Well, what other characters will appear in the anime...? Keep watching Hero until the end to find out what happens next!!