Hi there, I am in Vancouver and I want to hire someone to build a website same as kijiji.ca but I have no idea how many staff needed and how to management it, how manything I should do at the beginning, how big my hosting , register, etc... and I am not too sure how difficult or easy is it to own that kind of website? How much to invest, I want to hire someone to create my website but they don't know how to connect with payment system in Canada, but they have good price, well, so I want to know if I could install the Canadian payment system later on by a web developer in Canada? Lots of question, I am sorry, but I really need your advices. Any idea, please?

Sounds like you are trying to run before you can even crawl.
Do you have any experience in the web site arena ?

You need to consult a web designing & developing company according to your requirements.
You can also opt for outsourcing as it will save your money and provide good deal.