@nebulon Posting here the reply from project owner, in case it is useful to someone later on:
I'm wondering if it is possible to make notes protected by default?
Kind of. The protected status is "inherited" from the parent note when creating it. So if you make all notes protected then any new note created will be protected by default (since any possible parent is also protected). This applies while in protected session.
Also, can one edit the duration of a protected session (by default 10 minutes)?
Yes, in Options -> Other -> Protected session timeout