Japanese mother and American child with different surnames living in Qatar visit Beijin

My son and I are visiting Beijing this June for holiday.
My son has American passport, and I carry Japanese.
We were advised from the chinese embassy in Doha to apply visa for my son.

Question 1:
On the passports, my son's surname is different from my surname.
Will it be the problem to enter China?

If so, what do we need to do?

Question 2:
Do I, Japanese passport holder living in Qatar, need visa to enter China?