Welcome to Joplin @Zasoos!
To your first question: There already is a plugin for supporting journaling. Just give it a try, I have no experience with it. There is another thread here. And perhaps you’re also looking for using a template? There is a plugin as well for templates as far as I remember.
To your last question: Yes, as long as nobody kills your database using one of your lost devices, and as long as you stay synchronising your notes with your OneDrive, you should be safe.