Writing a new post I stumbled upon the Shortcut “Ctrl+g”, which opens the image uploader.
So I did a quick research and found this list: https://meta.discourse.org/t/keyboard-shortcuts/1589
Maybe it is useful for some of you! 
Edit: BBCode [key] doesn’t work on the FP forum…
There is a list of shortcuts on the forum already. It’s on the menu by your avatar 
@Chris_R OOPS, Sorry, didn’t notice that one… 
Good to know, though.
But: The one I stumbled upon doesn’t seem to be on there… 
Anyways, is there a list of BBCodes too?
Thanks for the fast answer, btw!
There is no official list of BBCode or Markdown Syntax that works on this forum, however most of them do.
Just play around a bit BBCode however seems to be as in CSS/HTML, with “< ></ >” instead of “[ ] [/]” . There are a couples that don’t work here, but work on the official forums of Discourse, for example “Spoilers”.
List of Markdown syntax: https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet
These all seem to work as well: http://www-bdnew.fnal.gov/pbar/htmlref.html
Some examples from the last link:
3 x 108
H2O
Deleted Text
These seem to have problems with quoting though… Anyways I will try some when I need them.
The problem was just that I did not know the exact syntax of quoting, since quoting does not work in a mobile browser (and I wanted to use it on the go). Also I am not very familiar with the formatting languages out there… 
EDIT: [quote=“John F. Kennedy (1917 - 1963)”]Mothers may still want their sons to grow up to be President, but according to a famous Gallup poll of some years ago, some 73 percent do not want them to become politicians in the process.[/quote]
Hey you can even insert any name in a quote! 