I had the same issues running i3 on top of Ubuntu, but Manjaro + i3 (https://manjaro.org/download/community/i3/) ships with a nice GUI for managing this stuff.

You can use the gnome utilities for this kind of stuff, I use gnome's network manager to select wifi and gnome-settings with i3-gnome for other tweaks. https://github.com/i3-gnome/i3-gnome

For screen management I use arandr.

The default i3 status bar actually has a tray for all of those things to run in. You just have to make sure to add the programs to your i3 config to be started.

For example, for my network widget I added "exec --no-startup-id nm-applet" to my i3 config file.

There are some taskbar utilities you can install but they are far, far inferior and more buggy compared to what you get with most popular window managers.

I wish someone will just give me GNOME (whichever version or fork) with all standard utilities, as well as settings for enabling tiling behaviour and shorkeys.