Oh hey… sorry I'm just now seeing this but I've been busy and I don't honestly expect to see much here usually, heh.
>is mature art ok? Your name suggests it but I just wanted to be sure
Our name has really nothing to do with Equestria After Dark. In fact, I myself knew of PAD long before the other thing. Not sure why that name was picked specifically, but a safe bet would be because it was the chat thread where people from /pony/ came to hang out in the evening after a long day of silly "argumenting" and possibly because of the ironic association with "EAD".
That all said, our name does not imply an interest in porn, and I'm sorry it could seem that way. Crazy I hadn't thought that this might happen and that it hasn't happened sooner really. We haven't had anyone try and post porn in our DA group, but I believe we want to keep it "SFW" in accordance with the general site rules of mlpchan, Ponychan, and whatever DA's regulations are on this. Basically, anything that's posted there should be able to be posted in any of the channels here outside of that special one Thony set aside for such things as porn. We of course don't care if you art your own porn images, and are free to join us and share your "lighter fare"… we probably just wont be interested in accepting "blantant porn"/NSFW images as a general rule.
>is there some sort of groupchat system or do you guys have a steam group or something?
We do have a steam group that many PAD members use, but it's not something that's really attached to the DA directly. The common thing that ties us together is "PAD" which can be found on this site every night on the /pony/ board. However, Thony is an old friend of the group and it was agreed that PAD's DA group would be inviting to his site's /art/ board. So anyone from here is welcome to join without having ever visited PAD if they choose. I guess the mentality is that friends of PAD are welcome there and everyone here is a friend of Anonthony at the very least. We would love to encourage people to come visit PAD though of course. It should be mentioned though that outside of PAD and this board, we try to keep things a little "exclusive" so that our small number of group admins can handle it and the group stays close knit and more personal. More details on this can be read in the DA group's journal.
>Is it purely show ponies or are variations such as anthro, humanized, OCs, etc. allowed?
Any art related to ponies is allowed. Of course, show ponies are the most popular submissions, but we have some humanized, anthro, and OC submissions as well.
It's kinda a slow and more personal pony group on DA, so you won't see a whole lot of new stuff day to day. At the same time, this makes it easy to browse the gallery and keep up with the art of your friends, and that's really what making it was for.
Hope that answers your questions, ans see ya around!