It may be a corrupted file in the game. But if uninstalling then reinstalling doesn't work, I'm not too sure. I've had the same issue in the past, but I believe it was because my internet had very poor connection and would disconnect then connect every 30 seconds or so. Antivirus programs could be halting it as well. Most antiviruses are loads of rubbish anyway, so if you have any, I would personally recommend removing them completely. At the very least, turn them off. They may be suppressing a script that is needed to fully activate the launcher. If you correct all of this, restart your computer then try it again. Hope this helps!

Some companions are not planned to come back like Zenith, Tharan, etc. If I recall correctly, I believe the dev team is trying to bring back all companions who haven't returned yet by the end of 2018. And I know some are already confirmed to definitely come back such as Doc, Khem Val, Jaesa, etc. It all depends. I believe they aren't coming back as alliance missions anymore (thankfully) and are coming back as part of new stories or side missions. But that's from what I have been reading, could be wrong. In terms of their character, not really sure. Although you can find clues as to which ones are trying to find you (such as Kira) or those who just don't really care (Jaesa) by looking at your emails sent by them after KOTFE starts. (I believe only the romanced ones will message you). Hope this helps!

I usually have the problem if I'm on a mount while I speak to someone. It may be a rendering glitch. Usually I just exit the cutscene and retry. Usually that works for me.