Reference counting and Garbage Collection have very clear difference: when the referenced objects are destroyed (not deallocated). In RC it happens when the count reaches zero. In GC it happens some time later. That difference is crucial for having or not having deterministic performance in your program.
Things are rarely as clear cut as we would want to believe.
It is. It might run when a behaviour finishes running, according to their docs.
Yes. In languages with destructors/finalizers called from the garbage collector, things can get very complicated. C# and Java have this problem.
Go avoids it by having scope-based "defer" rather than destructors.
With a bit of generics and lambdas, they can be made to even be more defer like.