WITNESS TESTIMONY
The door to the chapel was locked when the incident occurred. Only a witch could've killed all those people inside. She was already there. Kihihihi...
-Umineko Character & Analyze Book

They run out of time shortly after this.
ONO: But this torture will continue!
INOUE: Nooooo-!
They promise that next time, they'll find out who the culprit is, so you should definitely watch more. (Which, of course, means buying more DVDs I guess...)

Inoue wants to know if that reflects Ryukishi's real taste in women. Ryukishi explains that's not really what he likes. In real life, he likes girls who are honest and easy to talk to. When a girl is honest about her feelings, it means more when compliments you.

Ryukishi says that he's currently writing Episode 5, and at this point he wonders if twisted and warped characters have become his favorite. (I wonder who this is about?)

Inoue wants to know what kind of girls Ryukishi likes, out of all the characters in Umineko. Ryukishi says that when he started writing, he liked demure girls like Natsuhi and Shannon, but came to appreciate brutally honest characters like Eva and Beatrice.

Ryukishi says that if there is one thing the audience can learn from Umineko, it's to seriously think about what you're naming your children and using as a pen name.

was never meant to be his name in a professional sense- He chose it quickly over the phone for a doujin event he was participating in and has been stuck with it ever since. "What I want more than anything is a time machine, so I could go back and pick my name more carefully!"

Ryukishi explains that he was a fan of Final Fantasy, and there was a character from that named Rena. Fans gave her the nickname 07, and he borrowed that.

As of the time the special feature was recorded, the anime was at Episode 13, during Banquet of the Golden Witch. Ono smiles and says that even more characters will show up, but he thinks that this is all... The move on to Ryukishi himself.
INOUE: What is the "07" in Ryukishi07?

Even though the legend of Beatrice is about a woman, it doesn't mean that the witch or the culprit are a woman. In fact, it's absolutely possible the killer could be a man. It's even possible Battler is the culprit.

don't know how much I agree with this assessment, as an english speaker... But regardless, in Umineko, the term "witch" isn't meant to be gendered. Inoue agrees that "wizard" has a really different image, and wouldn't fit nearly as well as "witch" for this story.

The Japanese word for witch is spelled using the characters for magic and woman. Ono asks if this means the culprit is a girl. Ryukishi explains that it's not really like that. The Japanese word for witch has a feminine image, but the english word "witch" doesn't have that image

They rank the characters by bust size.
1.) Kumasawa
2.) Natsuhi=Shannon
3.) Kyrie
4.) Jessica
Ono nominates Maria as number 5, and Inoue goes "Really, over Eva?"

Eventually they give up and accept that deciding by boobs is not going to work for a murder mystery.