Adding timestamp entry to diary with insert-day command?

[Marc Coquand]

Heya,

I have began using diary, and quite like the simple format.

I'd like to change the default insert-day entry format, and add a
timestamp as well since all my entries are time-stamped.

Is there a way to do so?

Bonus question: Is it also possible to use org-capture to insert diary
entries with a timestamp included?

Sincerely,
Marc