Not sure what Province you are in. There are distinct advantages for incorporating, mostly have to do with limited liability, and tax advantages. These may or may not be good for you. The Industry Canada website or the Registry website for your province would be a good place to start.
For an ebay business, I would think that you would not want to incorporate federally, rather may want to do so with your provincial registry. Federal incorporation ensures that your name remains available throughout the country so that if you want to change provinces, you will also not have to change names.
The Revenue Canada website has information on collecting GST. As I am in Alberta, I have no knowledge of PST. If your worldwide revenues exceed $30,000 you are required to collect GST. It is actually good to collect it, because a large majority of your sales may be from outside the country, that you don't collect GST on. If you spend more in GST than you collect, you get a cheque back from the government for the difference.
You should be able to google business registration or incorporation along with your province, and there should be lots of information available to you about your options and the process.
Peter