Most of those you listed are already known to not fit perfectly yet, so you’re not unique there. If you install phosh Mobile Settings (an additional app to the regular Settings app), you can force any app to fit (although you might then need a magnifying glass to read what’s in the app after that).
With Firefox, you should install the Firefox mobile config package, and you might also want to install its Mobile View Switcher extension. See this forum comment.
Here’s the actual information about product warranty.
I don’t think there should be a problem sending it back for repair, at least.
Yes, there have been multiple updates along the way.