I remember reading before that the 5 most common names China (Chan, Lee, Cheung, Wong, Hor) originate from 5 generals/warlords who watched over China in a certain dynasty, therefore the people who were under their protection gave up their family name and replaced it with the general's last name. So the last name isnt too important :D

I heard having the same last name with your partner isn good in chinese cultures

who cares?