Is there a way to only view the markdown editor? I'm migrating from using Notepad++ and tons of text files. I got used to doing everything in ancient ASCII. I like the rich text for some things but for all my old stuff, I really need just a basic text editor type of interface.
You are aware of the markdown editor, yes? Well that's just a text editor with the exception of some minor things like continuing with bulleted lists once you start them.
The rest is just done through css. You would need to reset the classes you don't like using the userchrome.css file in your profile directory.
Also check out the appearance settings and Markdown setting to deactivate everything you don't want to use.
If there are specific things you don't like to have, it's best to mention those directly so it's easier to help.
However, at the end of the day, you need to recognize that Joplin is a Markdown application. There have been people in the past who complained that Joplin wasn't a pure text editor and it's not welcome feedback. Of course there may very well be ways to get Joplin to do what you want and generally people will be very helpful.
You can but the data is constantly being written to by the clients. So for example if something weird happened to a Joplin instance or you accidentally deleted a ton of stuff you didn't mean to then that change is propagated to the sync target and will be deleted on any other client that syncs to it.
A backup is independent of that and will contain the data from the point before the failure.