They've been scattered about a bit. You can find some from the Dash
(never thought I'd use that word) using Filter Results; many are also in
System Settings which is on the menu on the button on the panel you
click for closing down, at far right. Printers, displays, startup apps
are on that menu too.

On the whole I found it a nuisance which I'm coming to live with, to
have these changes in particular. Some things are gone altogether - iirc
I had to install xscreensaver because there's no configurable screen
saver any more. Also it's only in writing this that I discover you can
manage Groups if you go to the Dash - the System Settings on the panel
menu only lets you manage Users. Is that bizarre? Damned annoying,
anyway, I had to resort to the CLI when I needed to look at Groups, not
knowing it was on the Dash.

When you find something you reckon you'll need, pin it to the Launcher
and it'll be there next time - hopefully! (I have had some things
disappear, and for a while I couldn't pin The Gimp).

Hope that helps! Unity is still a bit frustrating to me, but it's become
an adventure rather than a temper tantrum over time.

Hmm, maybe the advice to try Mint isn't so bad at that. I haven't and
probably won't, nevertheless I haven't found that these changes are for
the better, they're merely slicker.