Bestie Brave is literally just Chromium again. Not to mention the fact that their CEO is someone who got ousted from Firefox for being a tremendous bigot. It's not a better alternative to Chrome, it's just the same thing again. It you must use a chromium browser, use ungoogled.
I tried it but didn't care to find out if there was a way to stop it from deleting all my tabs and logins, and I'm not relogging into everything just because I needed to close my browser.
It doesn't delete your stuff it just doesn't save your history and cookies as a save browser should do. For me that little inconvenience is fine because I get a big privacy benefit out of it IMO.
Eh, no. The original JavaScript has almost nothing to do with current JavaScript. More specifically, only the bad parts everyone hates are from the original JavaScript.
You can set exceptions to the cookie deletion in the security settings. I personally have everything I use frequently (invidious and stuff) to keep the login cookies.
Or you can just completely disable that feature.
I think the vanilla Brave Settings are better than Vanilla Firefox. Though something like Firefox with a custom user.js or Librewolf is a lot better than Brave