Let me share my experience about the issue:
Thus, I landed in Ottawa, ON. The situation is that since you have an international driver's license, you can drive with it for 60 days, after which Ontario driving license is required to drive. As for buying a car, I found out it's not possible to buy a car with int. license with the purpose of driving in the country, because the car can't be registered, neither insured. For this, you have to pass G1/G2/G driving test. Here, if you are a G1 class driver you need to have a fully licensed accompanying driver to drive with you (I mean, as a co-pilot) at all times during 1 year until you are eligible for G2 test and passing the test successfully. Take into consideration, your car insurance will hit quite high amount if you buy a car with G1 driver license. With G2 the idea of buying would be much more reasonable. One more note: If the driving experience on your international license counts more than four years, you may do your G2 test as soon as you pass G1 (written/knowledge test) without 1 year waiting period and no need for a fully licensed accompanying driver. So it is a good deal.
P.S. I had to rent a car for over a month and had driven with my int.license. Last week I successfully passed my G1 written test, next step is to book and pass G2 road test and theeeeeen get a car to buy!!! Keeping fingers crossed.
Wish you all the very best of luck!