Just come back from Canada, you need to inform the Car hire Company,with regards border crossing, I take it that you are flying into the USA, then you will obtain the visa on your entry, when you enter Canada you will be asked questions and maybe have to enter the passport control office to inform further information.be prepared to give your self enough time when crossing borders as it can take quiet a long time, we went Canada to USA and waited 45 minutes to obtain Visa. And that's pretty good as time goes for a border crossing. With regards tips for the crossing of the borders the only one I can give is be patient tell the truth .dont argue withe the guys and be polite at all times, it works this way. Re walking shoes make sure they are clean and put them in a bag in the boot of the car, this will ot be an issue. As stated his info is based on the fact that you are flying to the States to start your vacation.