Requirements regarding addresses and double entry visa.

In February we are going on a cruise from Hong Kong to Beijing, with a stop in Shanghai. We plan to spend 5 days in each of Hong Kong and Beijing. We have not finalized our hotel arrangements yet - do I need to do that before applying for our visas, as the form indicates that addresses and phone numbers are required? Also, is the double entry OK as we are making three stops in China? Thank you in advance for your help. / Bruce