You must have left the theater early. Well, just to save you the trouble of watching the films again...
1. Optimus simply launched himself into outer space to confront the "creators". This is where the new film will pick up.
2. Judging by the teaser above, the Dinobots will still be a thing.
3. Given the direction of this film series, there is no "calling for help", as both Autobots and Decepticons are fair game to the humans.
4. The film will come up with some convoluted plot to explain how Galvatron reverts to Megatron.
5. Re: Transformium - Don't know, don't care.
6. Though he got his vocal processor fixed by the Allspark in the first film, it got busted again in the beginning of ROTF for unexplained reasons. Otherwise, the producers think making him communicate with his radio gives him a better character.
7. Chicago was in the third and fourth films.
8. Hong Kong was in the fourth film.
9. Devastator was in the second film.