Are there any formal(izable) rules, or methods, or basic concepts in fusion kitchen cooking?
Fusion cuisine probably dates back centuries, as people and products migrated and influenced one another. Consider the development and spread of the noodle, for example. However the term "fusion" cuisine was probably applied in the 1970s in France and, slightly later, in America. The idea is simple. Ingredients and/or techniques from different cuisines are combined to create something new. In its best form, the result is unique, surprising, and delicious. However, critics, especially when the combination doesn't work, have sometimes dubbed it "confusion cuisine."
It would be difficult, at best, to define any sort of rules or basic concepts. Remember, the very idea of fusion cuisine is to break the rules or basic concepts of a single cuisine, by combining differing rules and concepts of two or more different cuisines. I guess the only concept I can come up with is that the dish has to make sense from a flavor, texture, and visual perspective. In other words, to be successful it must be appealing and delicious.
No, there are not- as Pieter suggested, is the answer here.
The reason for this is simple,
The basic concepts of cooking would obviously still apply, but it would be impossible to identify basic concepts of fusion cooking outside of these as there are so many variations.
As mentioned in the comments, one way you could look at is:
"The only rule of fusion is that it follows the definition of fusion"
In current day the term "fusion cooking" is popularized by chefs with non-French background and a traditional French cooking education.
They are schooled in France and take that experience and mix that with dishes from their heritage to create new dishes.
A notable chef to do that is David Chang