The following will contain spoilers:

Restore Content is pretty much updated with every new ScummVM release, and will continue to do so until the restoration is complete. Currently it's at something like 50%, maybe a bit more.

Playing the Restored Content mode in the GOG version is done via a shortcut that GOG installs, which may not be very visible. But they offer instructions about it here:
https://support.gog.com/hc/en-us/articles/360004386378-Blade-Runner-instructions-how-to-launch-with-Restored-Content-?product=gog

The restored content is basically additions to the Blade Runner engine code, as implemented in the ScummVM project, in such a way so that unused, bugged or untriggered stuff get restored. Thus, basically you can get newer / additional restored content only if you update ScummVM to the latest release version each time -- until the restoration is complete. Essentially, this means that GOG's version does not feature any new restored content until they update the ScummVM version that comes with the game. I'm pretty sure they'll do that but maybe after the work is completely done.

Now, out of the content you're mentioning:
- The hit and run dispatch should have been there originally in the GOG release (restored content mode) -- I think
- meeting Zuben in Act 4 is in the vanilla game. There's some randomness involved, but in any case it's not restored content.
- Confronting Runciter about Lucy is also in the vanilla mode -- but it requires meeting Zuben in Act 4 and asking him specifically about Lucy (you can only ask him about one thing before he takes off), so it's a bit rare too.

I don't really keep track of everything added with each ScummVM release, but other than small dialogue here and there, we restored the scenario with Crazylegs note (to Dektora or to Clovis) which implicates Grigorian and also may lead to Crazylegs arrest. And other than that it's some extra interactions with Maggie and smoother animations for her. There's probably more but these are the highlights in my mind.

We keep a more detailed list of restored stuff (but again probably not complete) in our wiki page at the "improvements" section:
https://wiki.scummvm.org/index.php/Blade_Runner#Improvements

Oh wow, meeting Zuben again is vanilla? I've played this game for years and never found him. Amazing I'm still learning new things.

One other thing: can you explain how friendship works with the characters? I know it can increase or decrease depending upon your actions, but I don't know all the triggers. Like for example, apparently Dektora favors you more if you don't speak to Gordo in Act 1, for some reason.

Each character has a friendship value for every other character in the game. This is very underused though, as the engine mostly deals with the friendship of characters towards McCoy. There are several things that can alter the friendship value, and they vary across different characters. I could make a list of what affects Dektora's friendliness but that would not be very indicative for how friendliness works for other characters.

Eg. for Dektora it matters negatively if McCoy keeps revisiting her in her dressing room backstage. And randomly it can affect her positively or negatively if he asks about the flowers. Dialogue options also can affect her.

For other characters it can matter if McCoy draws his gun, or if McCoy allowed someone to live instead of retiring them.

Now, what you mention about Gordo is also true. Characters can gather clues as McCoy does, but to a lesser capacity. However, characters also may exchange clues amongst their affiliates. So, if McCoy talks to Gordo as he's sitting at Howie Lee's Gordo surmises that he is a Blade Runner (as he just landed in a spinner). This clue can be exchanged and eventually reach Dektora. Also, other characters that are affiliates with Dektora can find out McCoy is a Blade Runner (such as Zuben) and they could also be the ones responsible for Dektora finding out. There's some chance and randomness involved, but basically what you say it's true, because in that scenario it is very likely that Dektora already knows who McCoy is and that he is a Blade Runner as he enters her dressing room.