question about HONG KONG Visa application

i am Vietnam citizen but i am studying in Canada. my friend from HK invites me to come Hong Kong for leisure from April 28 to May 1. After that, i will go mainland PRC to visit my relatives ( i already have chinese entry permit); therefore, i just want to buy one way ticket from Ho chi Minh ( Vietnam) to Hk to stay for 5 days then i will go mainland PRC for 1 week and half. Eventually, i will go Shenzhen to take the ferry to go HK Airport, and catch the flight to Toronto in May 10. Additionally, I buy one way ticket to HK and i will stay at my friend's house so i don't have the hotel reservation. I wonder i can pass the HK entry permit or not if i don't buy 2 way tickets and hotel reservation. Can u guys give me suggestion about my plan?