To indicate in questions and answers that keystrokes are being typed in normal mode or insert mode, should <kbd> be the convention?
Or should we use backticks?
Also, should we lead off ex commands to by typed in normal mode with the colon? :%!uniq or %!uniq? Or :%!uniq (hopefully not).
It is up to the personal preference and taste of the user writing the post. I don't think there is a single "best way". As long as the post is reasonably readable I would consider it to be fine.
One obvious downside of <kbd> is that it's awkward to type; so especially in long posts or posts with lots of examples backticks would be better (as in, lots easier to write).
To indicate keystrokes such as /, <kbd> is clear and natural
V}x}}p where typing out <kbd> for each character would be inconvenient, backticks are acceptable For Ex commands to be typed in normal mode, a leading colon as in :%!uniq is clear and natural
I think we should let the authors of the posts do what they feel is most readable, and make edits to improve clarity if necessary.
Trying to establish a convention for "this sort of markup means insert mode, that sort of markup means normal mode," seems like a lost cause. It will be difficult/tedious to enforce, and it won't be terribly obvious to new users coming across the site.
As a supporter of semantics, I don't mind sticking my neck out there: I think <kbd> should be used. <code> (backtics) is for code, <kbd> is for specifically for user input. As such, I think any typed commands should use <kbd>.
However, an issue is that <kbd> is sort of a "hidden feature". I don't think it's worth making edits just to make the swap, but I'd like to see it as the site preference.
V}x}}p?