Instead of how you are looking at it, I look at it like this.
The more kyubi chakra that is used, the faster he will get used to it. The faster he gets used to it, the faster the two chakras merge.
Kyubi cannot do anything but leak chakra behind the bars. Anything else has yet to be proven. We've seen naruto go berserk with the chakra, but the kyubi is far from berserk. Narutos just not at the ability to handle the power hes recieving.
Also, I think once the fourth had Kyubi sealed in him. It would make sense then for Kyubi to know the fourth.