Firstly, it was interesting to see that while Johnson grew up with the Transformers brand and was heavily influence by Geoff Senior for his art style, he has been removed from the modern Transformers content and discussion. So don't expect new characters to show up, even those which have retroactively become part of "G1" fiction, like Drift, Barricade or Windblade. The stories will instead have characters he is ore familiar with, though there may certainly be some G1 deepcuts.
The first issue had a passing remark regarding Megatron's absence and Johnson was not going to tell us more about that. BUT he did explain to us why he picked Bumblebee as the character to bite the dust in the first issue. At a basic level, the scene was made to establish to both new readers and the human characters in the story who were the good guys and the bad guys and how ruthless the bad guys are. Plus, since this comic is meant to be as accessible as possible, Johnson wanted to have well known characters, including the one who dies. This had nothing to do with Bumblebee's overexposure in the past 15 years, though it is interesting to note that Johnson never had a great affinity to Bumblebee growing up.
While the book has a very familiar premise for anyone who grew up in the G1 era, the book is meant to be accessible to all and Johnson asks us to leave everything we know at the door. The story he will be telling is fresh and new. It will be written as a series of arcs, with no end planned at the moment. At the same time though, Johnson is adamant to make each issue feel satisfying in its own right, as we saw with the first issue, with a full character arc for Jetfire. This is something extremely important to him.
A change we felt was significant was the talk of time. In most Transformers fiction, eras are measured in "millions of years" be it the Cybertronian war or the time between the Arc crashing and the bots awakening. Johnson changed that to "hundreds of years" in the dialogue since it felt more logical, but the impact story wise is minimal. It wasn't that big a decision for him and Hasbro had no notes on it. Speaking of Hasbro's involvement, they did give him feedback about the way he draws Optimus' hands. While they would want them to look less human, Johnson is sticking to the Geoff Senior school of robot hands, which are simply human hands with some rings drawn on the fingers. It is also less taxing for him, since he does have the double duty of being the writer and artist.
Speaking of that double duty, it gives an added layer to what we see in the comic and which characters appear. For instance, the cassette Soundwave chooses to deploy is Ravage. Johnson, as a writer, wanted to include this character that he loves and Johnson as an artist really wanted him in the story because it adds a different kind of element to draw. Him being an animal makes him fun to draw and adds contrast to the more blocky shapes of the other bots.
Those were the main parts of the interview, if you want to watch the full interview, you can do so below. But please be aware of some issues with framerate and the interviewer going on some random rants/tangents.