just saw my old post...
1) you don't need to export your car from the US and import it into Canada if you're going to live in Canada temporarily, but the insurance issue will definitely will be difficult to handle. that's the reason i did the import/export and got a Canadian license plate and drivers license.
2) given that you're going to live in Canada temporarily for less than 3 years, you can temporarily import your car into Canada and not pay the RIV fees, which is what i did.
3) you definitely do not need a broker to do export/import. i exported my car in person from the US (had to stop at the US Customs office, get out of the car, do the paperwork, and exit the US), and imported the car into Canada when i crossed the border -- don't forget to get Form 1 from the Canadian border officer who does your paperwork.