You can use the View/Note Appearance dialog to globally change the note font. Is that what you wanted?

If you are referring to the Home key, not quite. The Home key doesn't reset the tag and text search filters, it just puts the focus to the top of the list.

There's also a request to add autosave functionality to the editor, which is related:
http://roadmap.cintanotes.com/topic/8698-autosave-currently-edited-note/

Originally ESC canceled the edit.
Users complained that they lost their edits when ESC was pressed inadvertently.
This is why I made ESC to save the changes.
But I would hate to introduce another message box. What about making it part of the Undo function, e.g. "undo cancel editing"?

Could you please describe the steps needed to repeat the problem on the screenshot in more detail?
When I open and add some text the fonts are fine.
Are you sure that the "Previously saved text" is not formatted as "Monospace"? Please try selecting it and pressing Ctrl+M several times.

I find the idea interesting, although a bit nonintuitive. I'm afraid people won't easily understand the logic behind this behavior (they may already forget that they've opened a note).
I have one more suggestion:
1) Always keep the focus on the last note on ESC
2) Use plain Backspace as a shortcut for "All"
What do you think?

When you click a tag on the sidebar, focus doesn't leave the notes list.

This would be useful if you've picked the tag from the sidebar, as opposed to entering it in the search box.
It also allows for unification: it can be made so that ESC will always reset the focus, while Shift+ESC would always try to keep the last focus.