I'm talking about this sort of thing specifically:
https://www.theregister.co.uk/2016/04/28/windows_10_live_tv/

I'm considering a new laptop+tablet convertible to use as my onstage song chart tablet, but since new laptops always come with Windows 10, I'd need the "feature" linked above, and any similar popovers, do be disableable. I'm not a TV news station, but I would have a similar trainwreck problem if such a popup occurred atop a chord chart during a gig.

Anyone have tips on this?

I think that popup is specifically a Windows 10 upgrade notice that you'd get on Windows 7 or 8, so that wouldn't be a problem on a new laptop.

10 does have its own obnoxious behaviors, but many/most of them can be turned off in settings. The one I'm thinking of specifically is the Action Center that lives in the far-right part of the system tray, right next to the minimize all windows bar. Those notifications can be triggered by a bunch of different things, even certain websites. I recently went to the Washington Post website in Chrome and approved notifications, which gave me a pop up for breaking news. I turned that off because it's annoying and I also desperately need to control when I expose myself to the horrible things going on in the world.

Anyway, those notifications can be turned off:

Settings > System > Notifications & Actions > Turn off every last thing (although most of it will go when you toggle the first item)

As a bonus, I've seen performance improve when this is turned off.

I just turned it off again myself (could have sworn I did that), so I'm not positive how/when/if Windows Update will alert me. I still have the problem of it restarting on me automatically sometimes.

Ah, my mistake. I mistook the Newscaster screen shot as one of the Windows 10 update nag screens, which I've heard that you can't turn off or get rid of. Didn't realize it was a Win8 box nagging for a Win10 upgrade. Didn't look close enough.

Revising my question:

I've heard that when it's time for a Windows Update, that Windows 10 always covers your screen and nags you for a Windows Update and that it's always-on by default and that you can't turn off windows updates. That's the one I'm wondering if there's a way it can be disabled.

Windows 10 doesn't nag too much about the updates in my experience but does restart when it thinks you're not using the machine.

When it restarts it tries to restore where you were but many apps just don't work with that so if you have unsaved work you'll probably lose it. You should be saving always anyway, but something that probably will catch you out. Even just having your desktop all set up is annoying to have to redo.

That forced reboot is much harder to turn off. If you're using it, it will give the opportunity to postpone. You can also set times when it's best to reboot too. Also as long as it is actually up to date, it won't be an issue.

For an onstage tablet chart I doubt it will ever be a real issue for you.

Unless it decides to prompt me for a restart, or restarts, mid-song....

Certainly, but it should obey the hours you've given it. You could set a reminder before your concert to adjust the "Active hours" as it calls them. I currently have it set for 8am-8pm, which covers me most of the time.

You could set your hours to the times when you most often have concerts. I just wish they'd allow more than a 12 hour window. I assume they figure that they'll have the greatest chance of catching the computer turned on, but I'd much rather have it get more forceful about the updates over time like it used to do. I leave my computer on all the time anyway. I wish I could set active hours for 4am to 3am the next day or something.

I realise that's your concern. However, like I said you can set active times when it won't restart. It is limited to 12 hours maximum, but that should cover you shouldn't it? Also if kept updated it shouldn't be rebooting (yes that doesn't prevent last minute reboots).

Does presentation mode halt automatic updates?

:-O

There's a presentation mode? How do I activate it? And... Can I activate it programmatically (ie can I make it turn on when my song chart program is running). I must research this.

Seems there is a simple command:

Presentationsettings /start
Presentationsettings /stop

So, programmatically: Yes.

Does it stop all the other crap? Dunno yet. I only see settings for the screen saver, volumem, and background.