Classifieds website registration with government?

I already got a premium software because I plan to star professional in order to get a chance in this market.

i'm looking forward to star my website based business which I need to know the regulation and best practice business Registration, i know the type of registration for a business: Corporate, General partnership and sole proprietorship. What happen is: Is not an eCommerce "Web store" but I'm planning to integrate it in the future but for now will be a Classified website similar to Kijiji and craigslist.org to post job advertise, services, restaurant and more by the user who visit my website, register and so on.

I want to star Small easy to go back in case things doesn't go well do i have any options for that particular kid of business or it have to be Incorporating it? My question is for those kind of website, to start up which registration is more suitable? With a General business license for a sole proprietorship will be possible to lunch it and start up or need to be other license type, I don't want for now to go corporate because i'm starting it only by myself so I like to know an advice about how and easier way to register my website business name as a classifieds website.

I was reading that after i register could be any type i still have to go province by province and register in order to operate and get customers and visitors from other Canadian province other that Ontario? Do I have to register for HST tax and the other tax as starting my business or I have choice to do it after things are looking good with my website? I'm not that clear but i think tax will be pay after annual profit reach 30,000.

Thanks any opinion, resources or reference will be really appreciated and helpful.