So, the short answer is: Yes it is confusing.
Look at: https://forum.radsystems.io/t/for-all-users-of-phprad-2-7-3-vs-studio-classic/709
Depending on your needs 2.7.3 has worked great for some of us. I tried 5.0.1 IIRC and it is better at some things, not at others.
I keep hoping that 2.7.5 or something will come out and fix some of the bugs.
The first rule of 2.7.3 SAVE Often, with a new filename each time.
Rule #2 Do not copy a page. Ever. Your save file will be corrupted. (see Rule 1)
(You can save X.original, save a working copy as X.publish and edit the query or whatever, publish it to production and then revert to working on X.orginal. There are other frustrations. Other workarounds.)