Quick question: am I able to burn the downloaded installer executables (downloaded via the GOG Downloader program) to DVD or CD, then use them on my other computers with or without internet?

Yes You can

If you have a Burner and a empty disc, I would say yes... ;p

That's why we're here - No DRM. :p

You can even put them on your hard drive and install and run them without an internet connection. That's what no-DRM is.

Absolutely!

And if you are still not quite convinced, let me still say this:

Sure!

I cannot answer that, only you can. Do you have the necessary hardware (a computer with an optical-disc-writer), materials (suitable optical discs), software (Nero, CDBurnerXP, built-in software with whatever operating system you use, something else, and drivers for the disc writer), and knowledge (put disc in drive, start software, drag-and-drop files, click write... roughly)?

If yes to all, you are very likely able of burning the installers, and even bonus materials, to disc.

Sorry, the tickets are now diamonds, and GOG is now XBox1. No can do.

I think he was trying to beat around the bush about sharing said game with a friend. Which technically you can do, but you should support companies like this by buying your own games, and as one of the Blue Guys has said, they look at sharing a game as sharing a book. When your friend is playing your game, you are not.

Absolutely, GOG is all about DRM free games that you can backup if, how and when you like. So if you want to burn them to a CD/DVD/BD then you are very much welcome to do so and there are no technical measures to strop you from doing so.

Of course. There is a very limited number of games that have very large installers. For these, using a usb key will be the prefered solution

Well that's a step up. You weren't registered as a mime before, were you? You want me to fix that oversight?

BD discs and external harddrives are also usuable for such situations.