i have 40 hours layover in Xiamen travelling from australia to Taiwan . do i need visa?

i am from Australia. travelling with my family to Taiwan for 2 weeks holiday. in may way to Taiwan i will have 40 stopover in Xiamen. and in my wasy back to Australia i will have 30 hoyrs stopover again in Xiamen. do i need visa for each stop over? how much it cost per person. i would like to staay in hotel and tour the city in each stop over. any recommendation?