UK citizen applying for Q2 visa 2 year multiple entry?

Q2 type: Issued to those who intend to visit their relatives who are Chinese citizens residing in China or foreigners with permanent residence in China. The intended duration of stay in China is no more than 180 days.

How much will it cost to apply for a Q2 type with multiple entry for 1 year vs 2 years.
Also what documents do you need? ie Airplane tickets? Relatives Citizen ID? etcc..

Thanks