I will share my experience if it helps. You should study the driver handbook well before you try for the exam. On my written exam (Alberta) which was actually not written, it was taken on a computer, they asked about the meaning of some traffic signs, they asked about speed limits, they asked how close you can follow behind an ambulance (that one I remember because I did not know it and had to guess). They also asked what is the parking lane for on the highway and what are the speed limits and time periods you have to adhere to them in a school zone or a playground zone.
If you fail the written exam, you can take it again the next day, it's not a big deal. A couple of years ago, it cost around $16 or 17. I don't know how much it is now.
Once you have passed the written exam and have qualified to take the road test, you book an appointment. I can't speak for Ontario but in AB, they are booked by registry offices and you need to bring a car. If you do not have a car, you can often arrange to rent one. You may bring a car with an automatic transmission if you prefer. You should be very careful when driving. Do not exceed the speed limit, always properly mirror and shoulder check as well as signal before you change lanes. When he makes you park, make sure you signal when you leave the parking spot as well. I only took the basic road test because I could not prove my driving experience and it was easy. I can not speak for the advanced road tests but I knew someone with a lot of driving experience who failed it only because he was driving a little carelessly, not keeping both hands on the wheel, not properly signaling lane changes or shoulder checking etc. If you fail it, it is also not a big deal because you may take it again, maybe not right away the next day and it costs a bit more but it's not like they bar you from driving forever if you fail it the first time.