A: Welcome to the site. This is a great site for you to tinker around in, and learn. You should realy go to the introduce yourself section, and, well, introduce yourself.
1. Registering your bike is only required if your state requires it. I'd look in the Winnipeg DMV (Department of Motor Vehicles) or whateve you guys call it. For us State-side, every state has it's laws. Some will say if it's over 49cc, you have to register it. Some say it's all depending on how the production is, under 5HP you don't need to register, over 5HP you so. Also, age might have something to do with it, too.
2. It will depend on how much you weigh, the hills, the sprocket, and the state. If you don't want to register the bike, or get a license, the 49cc will probably be fine. The 80cc kits are honestly 66cc, and they are a little bit more powerful (torque), but you're not trying to win a race, right?
3. It again depends on the state. In my state, you don't need a license for anything under 150cc. In some states, it's 50cc. In some, it's age related. In some, if it has an engine and wheels, you need an operators license to operate it. So, you need to get into your state's regulation, and do some research.
One thing is for sure, you're going to have a lot of fun building, riding and talking to people about the motorized bikes. The low cost of ownership, upkeep and maintenance , and rediculous gas milage will turn heads, I promise you!!
