non russian citizens applying for transit visas

I am from New Zealand, living in Moscow with my American husband & son. I am taking my son to NZ for Christmas and have a very long stopover in China. We have booked a hotel room a few minutes walk from the airport in Guangzhou but have since learned that we will need a transit visa to be able to stay there. Is this the case? Also, we have limited documents with us in Russia - just the visas in our passports. Do we require any other documents?