Travelling overland

My husband, daughter and I are planning to travel to China in September this year - we are applying to study Mandarin in Guilin and we will have documents from the institute to that effect - we will hope to visit Chengdu on the way for tourism. Would we need to provide proof of that hotel as well as the information from the study centre?
Plus we do not fly and will be travelling overland from Kazakhstan so will not have air tickets, and trains can only be booked 30 days in advance - is that okay are we still able to apply for visas? .
And one last question - this forms part of a longer journey to Australia to visit my sister and we would planning to come back via China and studying Mandarin again - can we apply for both visits on the same visa application form?
Thanks in advance for your help.