You will get alot of advice from the members on this board. For answers on tools to use, definately take advantage of the suggestions and explore what may be best for you.
Here is a good, recent discussion thread to look at: http://forums.ebay.ca/thread.jsp?forum=44&thread=300002624&modified=1084988159488
It may have the answers to your questions about automated tools to help you in your eBay business.
Under the tax laws of this country, you are required to register your business provincially and federally where filing and remittances will be dependant upon your businesses' annual projected and then later, actual income. You can go here to start: http://www.ccra-adrc.gc.ca/menu-e.html
Not knowing your professional background, I would suggest that you attend some government sponsored information and training classes in setting up and running a business.
Not only will these courses provide you with some insight into licenses that you will need, sources of financing, basic business accounting etc., they will also help you obtain any loans, should that be part of your business plan and business needs.
Check with your municipality as they are usually the ones that host the programmes that are joint ventures between the federal, provincial and municipal governments.
The other advantage you get is deveoping a network of support people in your community.
You have alot of questions that could require alot of detailed explanation and much of that will really depend on where you want to go with your business (how big, target markets, limited to ebay sales etc.)
Far too much to get the type of help from a forum.
If you cant find the resources for the classes I was speaking of, email me and I will get you a contact to make your inquiries through.
Malcolm