I've seen different depictions of sailor pluto around, and sometimes her skin is brown and sometimes her skin is white, is this something made by fans or is it the original? Because I know some colors often change going from the manga to the anime, sometimes even from one edition of the manga to another, so which one is the "canon" skin tone?
Where did the symbols for each sailor come from? I know some of them are the originals from mithology, but not all of them.
Did Usagi ever get to university? I haven't watched the anime to the very end yet, but I like to imagine Usagi and Mamoru being cute together in university, but she was never such a good student, so I'm not sure.
This has been very controversial in the fandom ever since Pluto was introduced back in the 90s, lol. Pluto's skintone has been WILDLY inconsistent in every single medium she's ever been in. I actually made some collages years ago demonstrating this.
Here she is in the black and white manga, where she is consistently portrayed as having dark skin:
But in Naoko Takeuchi's colored illustrations, she's notably lighter (but still darker than the other Senshi)
And in the 90s anime her skintone basically has no consistency, lol. She's very pale in R (2nd season) but tan in Stars (5th season), and artwork of her is very inconsistent.
In the reboot of Sailor Moon (Crystal/Eternal/Cosmos) she's again pretty pale, but her skintone is more consistent.
So, to answer your question: I honestly don't think there IS a "canon" skin tone for Pluto just because within canon they've never settled on one thing. My rule of thumb is just that she should always be noticeably darker than the other girls, something that all portrayals of Pluto usually adhere to.
You're in luck, because I made an entire analysis post about that here!
Did Usagi go to University?
It's never discussed in canon, but I'm leaning towards "no." Usagi hates school and isn't a good student, so I can't see her wanting to go to university. Plus, she becomes Neo-Queen Serenity at age 22 (as revealed in the manga), so I bet she always planned on having that to fall back on, lol.