Shop around on the install. I got my EVSE installed, cable run to the garage, panel upgraded from a fuse to a breaker panel (which I was going to do anyways) plus the certificate all for under 2000. The first guy I had come out quoted me over 4000 for the same job. Now all installs are going to be different you may have a difficult or long run for the cable but is best to shop around. Use the http://www.esasafe.com/
website to search for an electrician. I found it is best to go with the smaller ones. Can also search on Kijiji.
As for using just trickle charging. It might be fine for now but in the winter when you want to preheat off the grid you may run into issues. Again depending on how far you drive it may work for you.
After I posted about not getting and EVSE from the US there was some discussion about this on the Canada Leaf Facebook page. It seems some people bought in the US and were still able to get the rebate. The one person bought at Home Depot US I think. So it may be as long as the business exists in Canada and the US the rebate may still apply. But again if they have a rule about buying from a Canadian supplier then they could deny you if you don't buy from one.