Not really, just use your DE's software manager.

This isn't dependent on distro, but your DE, which determines the entire UI. It's like complaining the settings menu isn't consistent between Google's Android and Samsung's Android. For reference, under Gnome, you have to install Gnome Tweaks, then just open that and go to Startup Applications in the sidebar.

Heavily depends on what you want to do. Many use cases (such as Minecraft) don't really need the terminal at all.

Yeah, that's not at all unique to Linux though

Minecraft Java is officially available on Linux, and should be available in your software manager. Minecraft bedrock is not available officially, but a program called Minecraft Bedrock Launcher is available that will let you run the Android version of the game.

I'm not sure exactly what you mean, but media should be available to mount in the side bar of your file manager