Using the accelerometer MPU 6050 with the library Makerhub and Arduino.What's the purpuse of clock source and the I2C channel?

Hello everyone! I'm new using arduino and labview and I try to measure vibrations with the accelerometer MPU 6050 using arduino. I have seen a few of tutorials and read a little all about the topic.

My question is about the library Makerhub from Labview to the accelerometer MPU 6050. I do this program following a tutorial :

1._ how you can see, the block of open have a branch whose name is "clock source" that is associated to the constant see it on the screen (Internal 8MHz Osc). This confuse me a little becouse it's seem like if the MPU 6050 is the one that generate the clock pulse. And for what I read about the I2C communications protocol the device that do this is the master, that in this case is the Arduino. And the other hand, it's possible choose other constant values like :

Someone can explain me what's mean every possible opción and why I should use the first that is "Internal 8MHz Osc" ?

2._ Why the thre blocks : Open, read and close are associated to one branch that is a constant 0, that define the I2C Channel? Why can be needed several Channels? . I mean, this confuse me a little becouse for what I read all the devices that are connected with a i2c bus, only need one channel, becouse all the devices are connected in series like this picture :