The only complaint I can't discuss about is the first few because I didn't even know you could save with right-click and don't remember the Missing Tapes Quest (if this is the one that is unfinished, I think I didn't bother starting it).
Are you trying everything without help, following the in-game walkthrough, or the external guide on Page 1? I've had no issue with the game on 1.7 using a combination of these and most of these complaints seem like you're complaining about bugs while trying the game without bothering to consult the available guide...
2. Is definitely completable - I followed the same route
3. I believe I found the cat somewhere in the school (check guide)
4. Does the game not indicate where you can get more water from? It did for me.
if I remember correctly
5. Indicator in-game says that it's in development and guide says it too... Not sure how that's a bug.