Welcome, Hal. Lots of older folks use Ubuntu, and lots of older folks are here on AskUbuntu. The kids here can be noisy...but kids have always been noisy.
"Keeping up to date" could mean two things - security updates or latest-and-greatest versions of software. A lot of people get the two mixed up, but there's a difference. Security updates keeps your system safe from many (not all) forms of hacking. Latest-and-greatest includes security updates plus new non-security features and changes. Some people dislike those changes, especially if a favorite feature gets hidden or removed.
ALL supported releases of Ubuntu get security updates. You don't need to worry about that. If you like your desktop the way it is right now, and don't want it to change, then stick to an LTS release of Ubuntu. If you want to see the new stuff, then try the standard every-6-month release of Ubuntu.
You SHOULD have a way to backup your personal data (located in /home) in case your machine gets clobbered by water or cats or kids or a power surge. Lots of ways to do that.
You DON'T need any separate partitions (with one exception for EFI, used for booting). You DON'T need a separate /boot, you DON't need to use PPAs. That kind of stuff is completely optional, do them only if you wish to. If you let the Ubuntu installer stick to the default choices, it will build you a nice, sane, usable system...and that's exactly what we recommend to most new users.
Some new users, after a few months, change their partitions, try PPAs, install another desktop flavor, or otherwise customize their system. But lots of people stick to the basic install quite happily for many years.