Interests being type related or not type related
In my opinion interests are largely NTR, only difference can be seen between logical and ethical types. It's less about the what, but more about the why and how.
Type is about what you like (value of functions) and about what you think more (strenght of functions).
As interests is what you like and about what you think - there is strong dependency.
Interests to weak and nonvalued regions are more rare and lesser expressed. They are possible, can be trained and to get significant time but it's not common. Non Jung-types reasons may _also_ predispose to interests and occupations.
Types are about more common, mainly. In this sense - interests relate to type. This relation is not absolute, certainly. Types are among factors for what people do.
It could also be that some interests get wrongly attributed to certain types as well. Two people of different types could like the same thing but they will go about it in different ways and have different reasons for doing it.