It's a bit of a mixed bag. Some IDW Transformers comics fit neatly into the overall canon, while others might have elements that are more open to interpretation or might not be fully accepted by all fans and official continuity.
Transformers comics are typically seen as canon. But there could be exceptions based on different editorial decisions or story arcs. Generally, though, they contribute to the overall lore and continuity of the Transformers franchise.
The Transformers comics have had multiple creators. One of the early and influential creators was Marvel Comics' team, which laid the foundation for the franchise's comic universe. Later, other comic publishers and creative teams continued to expand and develop the Transformers comic storylines.
It's hard to give an exact number as new Transformers comics are constantly being produced. But there are definitely a significant amount available over the years.
The ownership of Transformers comics can be quite complex. Sometimes it's held by major comic publishing companies like IDW Publishing or Hasbro themselves.
The creation of Transformers comics involved several contributors. Bob Budiansky and Simon Furman are notable names associated with its inception. Their creativity and storytelling skills made the comics a success.