Travel to Shenzhen, Meizou, Dau, Haikou, Hainan, Guilin and Hong Kong. Please put them in order.

Since you come from Canada, it is suggested to reach Hong Kong first. Then you can go to Shenzhen directly. After that, you can reach Meizhou from ZH directly. What do you mean by "Dau"? Then you can reach Guilin and then fly to Haikou. Then you can go back to Hong Kong and go home.
July to early September is a typhoon season for Shenzhen and Haikou and you can just stay in your hotels to avoid it. But in my opinion, it is suggested to travel to these places in September, because the scenery in these places will be good and few typhoon happens at that time.
It is hot in most of these places, because it is the summer time for all these places. The average temperature is about 28C or higher. so it is suggested to avoid that period.