You are welcome to continue posting X links. They just aren't very impressive to look at and require opening a new tab to view.
I don't know if the quote function has a character limit per se beyond the regular character limits for posts which is 60,000 characters. The display of quotes is limited by size. When they are over the allowed length, the quote will show a "click to expand" at the bottom of the quote that will reveal the remainder of the quote.
If you preview your post you can tell if you quote will need to be expanded.
Profile messages are limited to 600 characters
Maximum images per message is 12
Maximum image embeds per messages is 6
These are arbitrary numbers and can be changed if needed.
The only difference between a regular discussion thread type and an article thread type is where the user avatar and stats are displayed. Article type will show them horizontally at the bottom of post.
Also, with appropriately sized pictures,, which can be adjusted on the fly, they can be aligned left, center and right to wrap around your text. Here is an example of an article type thread with a wrapped picture:
https://www.citadel-81.com/xen/thre...-fake-news-before-you-even-make-a-choice.124/