the point is there is not any new defined I2C. So does not matter if I put that resistors or not. Or it does matter and I do not know!
Not sure I understand those words. You always need one set of pull up resistors on each I2C bus.
it is still black. because it does not considered as a header.
No it is still black because someone did not put in the line in the keywords.txt file that makes it change colour, that is all.
Question: If this command of #include <i2cMaster.h> really defined a new couple of I2C pins, and I did not use resistors, what may happened?
Then it would not work.
Question: is 4.7 kohm is enough for pull up resistors? how should I put it?
Yes, wire them from signal to +5V.