1. Flying back will get you to a high relationship level for this officer very fast, which is good. On the other hand, the flight back does not increase the relationship with any officer, which is bad, and gives you some morale boost. We will see what has the better effect on gameplay. As long as serving only one officer is not a working winning strategy, I think it is okay.
3. I guess my main advantage was that both boni kicked in right from the beginning of the game, whereas other boni take a while (Major / high relationship bonus), and it is a race whether they first kick in or you first run out of money. Reducing base payment would make the game really hard if you do not have a station type bonus. I would rather nerf the bonus a little bit, maybe to 25%.
4. A faster increment of the relationship might not be sufficient. My level 6 officer would be level 8 or 9, the level 5 officer at level 6 or 7 (he was closer to 5 than to 6), maybe one of the level 4 officers would have been level 5. However, this is fine tuning, I would first increase the relationship speed and then check whether there must be additional adjustments to the game length.
My browser is to configured to delete page content on close. As you do not play the game in one go, shutting down my PC deletes the save games. Therefore, I play the client version.
If it not too much effort, I would keep both versions. While my browser settings are common, the web version is good to have a quick look at a project. I rarely download client versions before testing them as web version.