(Anyone can add to this, not planning on a follow-up)
Frankly, you didn't know how to think about this. The fact that you were now a devil was jarring, to say the least. Just a day ago you were a human that was living his best life but then you died and became a devil.
That by itself would be cause for concern, but you were also shrunk in the process of turning into a devil. Sure, you had wings now which would eliminate the struggle of movement, but despite your size, you didn't know how well your body would compensate with your ability to withstand pain. For all you knew someone could slap you like a fly and you'd just splat, on the flip end you could have been physically strengthened to the point where you were near impervious to damage.
It seemed as though Rias understood your concerns and spoke up, saying, "Devils by nature are incredibly sturdy, and I suspect this interference, instead of shrinking you it condensed you, making you much more impervious to damage. Of course, I'm not certain of this, but I am very confident in my conclusion. So rest easy, knowing that you won't simply get stepped on and die."
You heaved a sigh of relief. At least you weren't going to die by someone accidentally. With that answer solved, you moved on to the next question. "Is there any way you could turn me back human?"
"Sadly, no. Right now you are living on devil magic alone. If I take that out of you to turn you human you would die instantly. Maybe in a couple years when your body gradually restores its own life force could I turn you human again, but it isn't strong enough yet."
With that out of the way, all your questions were answered. There was only one thing you could really say at this point. "Nice to meet you, Master."
"Fufufu, just call me Rias. We're family after all"
"Of course, Rias"
"With all the explanation out of the way, I figure you should meet your fellow peerage members. They're all girls, so I hope you don't get too flustered. I'll show you to them later today since class is almost over."
And with that, Rias turned around and unashamedly showed you her shapely naked ass. You immediately turned around only to hear Rias giggle behind you. "Fufufu, shy are we? I fear what Akeno will do to you."
You blushed even more, not that she could see. After a minute of calming down, Rias called out to you. You turned around and saw her in a school uniform with a skirt that was way too short for its own good. Rias dropped out her hand and said "Hop on.", which you obliged. Her hand was warm and soft, yet you could feel immense strength in her hands. Rias dropped you on her head and started walking towards the door. You held on to her long strands of red hair, scared out of your wits of falling despite your new wings.
Rias opened her door to what you could only describe as a lounge with one big desk at the end. Based on Rias's previous words, this was probably her main meeting room for her "family" meaning it was also where you would meet the other members of Rias's "family". Rias gracefully walked over to her desk and placed you down, sitting on the chair for said desk. You and Rias simply waited in silence, having already said everything you needed to say to each other. The door at the far end of the room open, and in walked...
A: Sona Sitri, having heard of a new peerage member being added.
B: Akeno Himejima, eager to greet her new kohai.
C: Koneko Toujou, eating her chocolates like always.
(PS: All members of Rias's Peerage is female in this line. Kiba is female and Gaspar is female. Issei doesn't join peerage because pawns are already used.)