Considering how common it is to see Unicode Emoji these days, along with Furry Network's mobile support (where emoji is most prevalent), it would be worth supporting to some extent. Even an implementation of the freely-available EmojiOne project (used on sites like Discourse and Slack) would be welcomed, and they do offer developer tools for this purpose.

Agree, limits like this need to be stated outright, otherwise it just leads to user confusion/frustration.

If importing from Weasyl is implemented, Furry Network will need to account for submissions that link to external media. Weasyl currently allows multimedia submissions to embed media from Bandcamp, Soundcloud, Vimeo, Vine, YouTube, and Sketchfab (3D models and scenes).

Publishing a folder of works at once would be interesting! Admittedly, I've since realized that multiple submissions can be edited at the same time, mitigating a lot of the hassle from posting submissions one-by-one. (Other sites would require the artist to go through the entire process for every single submission — select submission type, enter title, copy/paste description and edit next/prev page links, upload file, submit, repeat process for next page. It sucks.)

Still, having some way to limit submission flood and keep sequential works in one place would be great. I suppose if notifications could determine whether a single submission or a folder of submissions has been posted (or updated, for ongoing series), that would work out just as well.

Pixiv has a feature called "Image Response" (unfortunately no official English documentation) which could fit what you're describing, a way of chaining submissions together. Pixiv's way of setting it up is kind of convoluted, but the end result is pretty neat! If you have an account, you can see it in action under the comments for this image or this template.