How much is a trip from Lo Wu to Hung Hom by East Rail Line?

I want to travel from Lo Wu to Wan Chai.

Also, would it make sense to buy a Tourist Day Pass? I understand that I cannot use such a day pass from Lo Wu, but can I buy the Tourist Day Pass at the Lo Wu ticket counter and use both, a single ticket to Sheung Shui, then the day pass to Wan Chai?