'Does this script always use https?' and 'Can you pause downloads to continue later'?
Also - most likely asked before, but 'does it verify if game was updated?'. And, if yes - 'will new copy be downloaded separately or instead of existed? (e.g will already downloaded files be removed or nope)'.
And yeah, almost forgot - does it work for account, protected with email codes?
Assuming you're using my fork:
It uses https as much as downloading from GOG in the web browser does (which I think is everything, I'd have to check a gog-manifest to make sure that the download URLs GOG gives are HTTPS and don't have it handy right now). (AFAIK this is true for the original version too, I haven't changed anything in this respect).
You can generally interrupt the script (using standard break commands for your OS) and resume it later, you might sometimes have to redownload a small amount of data (files are downloaded in chunks and a partial download will be resumed from the last valid chunk). Obviously if you use a forceful kill method while it's writing to the manifest files, bad things will happen, so don't do that (the program will ignore polite kill requests while it's in the middle of such) but writing to the manifest files is kept to a minimum. .
Shorter Answer; Yes, you can stop the script and resume from very close to where you left off.
The normal behavior is to download everything, with options to take GOG's word on what's New / Updated , GOG has historically been pretty bad about how accurate it's word is on that, but they are getting better. The dev branch (which will be become the main branch when I'm happy with it) has different behavior: it downloads only what GOG says is new/updated with an option to download everything (introduced to be kinder to the servers). I recommend only doing a full update once a month or so (and do an update of a specific game before you install it to make sure it's up to date).
The default behavior if a no longer used file exists is to "orphan" it (ie move it to a separate subfolder , where you can decide what to do with it later). If you're wondering why it's because GOG has in the past deleted certain extras without immediate replacements or accidentally uploaded corrupt files (they generally fix this pretty quickly but it's not a surprise you want if you're without internet access when you find it).
Yes, it supports the email login codes , though things can go wrong if the Recaptcha is triggered, in which case you need to export cookies.txt from a browser and use that instead.