Your comments
I'd note that even InkBunny which supports multiple images per submission, doesn't support separate ratings and separate tags. As a result, I often see separate submissions even on IB.
Implementing full separation won't be easy...
The way comments are implemented right now screams "COMMENTS ARE GARBAGE". They're single-line, limited to 1000 characters, not threaded, put into a tiny space which is close to impossible to navigate. If you leave comment design this way (I'm not just talking about side panel vs below image, I'm talking about all issues), it'll harm community. The harder you make commenting, the less people will bother to comment; the harder it's to read them, the less people will read them, the less people will be motivated to comment.
The first problem with the side panel is that it's tiny. You try to fit all content into it. Look at the pages on FA. On popular submissions, comments are 80% of content, often more. And you're trying to fit 80% into 20%. It's impossible.
The second problem with the side panel is that you try to fit multiple, very different usages into one design. What usages?
1. "I want to just view images." People who want images and nothing else. Go to DeviantArt, open any image, press Left and Right buttons. Notice that image is always loaded first, you can quickly switch between images and browse the whole gallery this way.
2. "I want to evaluate an artist." They want to switch between popular images of an artist, they may look at titles and maybe descriptions.
3. "I want to devote some time to this image." They want to read title and description, discuss art in comments.
Your current design tries to do everything and fails at every single task.
1. People who want just images can switch to full view, but can't navigate in this mode.
2. People who want to naviagate a gallery, get navigation at the very bottom of the side panel, they have to scroll it every time.
3. People who want to read and discuss... well, they get the shortest stick. It's close to impossible. Title area is tiny, without wrapping. Description is collapsed and tiny. Comments are barely usable.
Overall, the current design is currently the worst that can be imagined. It doesn't do a single thing right.
As far as comments go, there're many obvious suggestions already posted here: increasing character limit, threading etc. I don't think I've seen complaining about single-line comments by default, but if there isn't, I'll create it. Overall, just moving comments below isn't enough. If you want activity of viewers (and many artists consider this one of the most important factors), you need to fix a lot.
https://support.furrynetwork.com/topics/289-/
https://support.furrynetwork.com/topics/455-/
etc.
If you want my opinion on design, I think comments should be moved below the image. Permanently, no switches. There's enough content for the side panel already, more than enough actually. You've made title and description unreadable and navigation barely usable. If you want them to be useful, you should let them occupy more space. See https://support.furrynetwork.com/topics/1006-/ for more details on rearranging content in the side panel.
There's also a suggestion to move description below image (see https://support.furrynetwork.com/topics/707-/). Considering descriptions vary from artist to artist (some leave them empty, some put stories there), I think a switch "side panel / below" would be useful. It'll also satisfy people both in categories #2 and #3 described above: either navigation or titles+descriptions could be prioritized, depending on preferences at the moment.
And finally, regarding people from category #1. While it's not top priority, navigation like on DA could be useful, with inheriting submission list and sorting from searches and galleries, maybe with hiding side panel completely.
The difference is most likely caused by time zone being changed on FA's server. That is, they don't bother to convert to UTC or a specific time zone, just use the default one. And in case of posted time, they do bother. Well, I suspect.
If dates are included (which I don't find particularly useful, but whatever), I'm against adding noise like minutes and seconds. Time tends to be random and just reflect artist's time zone rather than anything useful. If you want to sort by time, submission id is much more reliable anyway, as it's guaranteed to be unique.
Original file names are a bad idea, as many artsts don't bother to name properly, plus original file names often enough leak private information. I've seen many times "anonymous" art with artist's and commissioner's names in the file name on FA or IB. Generating file names from submission titles is much more reliable and safe.
Limit of filenames in Windows is 260 characters, so if a filename longer than 100 characters causes you poblems, you may want to consider using less deeply nested folders. :D
You shouldn't quote huge blocks of multiline text really. It's a bad practice. You should only quote relevant pieces instead. And for this, markdown is perfect.
There's an exception of quoting text from somewhere else, that's when multiline quotes actually make sense, but a simple toolbar can solve this.
Comments are currently third-class citizens, as well as descriptions and even titles (which I find ridiculous).
https://support.furrynetwork.com/topics/1006-/ — my suggestion with an alternative solution. I think description in the side panel is nice (if it's expanded by default and not too long), but having an option to move description and everything else below would be great too.
Not only comments area is tiny, but comments are single-line by default. That actively harms discussion.
Aren't there two method for this - one which replaces and one which appends? All modern browsers should respect that.
Customer support service by UserEcho
I bet you don't quote poems every day. It's an exception. For this exception, HTML/BB works better. For most everyday uses (that is, quoting comments of others), MD is much cleaner.
By the way, if you quote articles, you'll only need one ">" per paragraph, so you'll have to quote a really huge piece of text to make BB shorter than MD (unless the text is preformatted, but you should reformat it before posting then). With the current 1000 character limit, it's close to impossible. :)
YMMV, of course, but I seriously doubt a considerable percetange of users quote poems every day. :)