For some reason, my editor always creates an extra space every time I start editing. Thankfully, I've figured a way around it; I just go on to "show changes", find where the extra gap had been created and close it.
Glad to see it has been fixed! I'll go ahead and take a look at your contributions to see what I can fix right now of the pages you edited recently.
As a content moderator, best practices would be to use the source code editor (instead of any visual mode given) and see how pages are formatted. Generally the other two editors are buggy and do some wacky stuff to pages just by viewing it; adding extra spaces is just a start. True classic source text editor is a minimal amount of extra code, and it shouldn't be too difficult to pick up.
I believe you can disable the visual editor tool through "My Preferences."