Boarder runs are a manipulation of the system on tourist visas they been cracking down on cause of abuse and tourist that cause problems entitlements and even mules.
Yes, IDP is only good here for 90 days, if you are going to stay here longer then 90 you can take their classes and test or move your license over via reciprocal agreements but its eaiser to just take their classes and test, how long yoir license will be valid for is based off the visa you have
You can yes but if you have all the info needed you can do it 3 days before arrival. They will ask you for confirmation you filled it out. If you have not they will pull you out of line to a board with qr code to do it.
I agree if you are going to take part in something is up to the person to know all the legalities as I understand the law the land lord will have to deal with it