Is it mandatory to have hotel reservations when applying for a tourist visa?

Hi, plan on vacationing in China from mid-April to early May. There I will meet relatives who are coming from another country, they are going for business purposes as well, for that reason some days I will be by myself and some days we will all be traveling together, but it depends on what their schedule is.

I plan on arriving in Guangzhou (I'm coming from New York), and we plan on visiting Shenzhen, Beijing, and Hong Kong on two different occasions, but due to their uncertain schedule we will decide on what dates once we are inside China. This prevents me from scheduling hotel reservations at the moment, can I still obtain a tourist visa by showing to the consulate with just flight tickets?

On a related question, I plan on visiting Hong Kong on two separate occasions, each for less than 3 days. I understand I don't need to have a HK visa for that, would I just need to show my passport with a Chinese visa when doing HK customs? This also means I need a multiple-entry visa right?

Thank you!