A wire transfer is the same in the USA or Canada. It's a bank to bank transfer. It can take few days before the seller is notified it has arrived. Last vehicle I bought down South it took 4 days before the company received notification, but that might have been their corporate structure.
As to the auto transport company .... if they are licenced, road tax, MFT, ect ...same as any trucking company has to pay for opperating in any state they can opperate in Canada.
If your going with a broker to handle the import let them handle the transport also. That way if there is a problem, they get the paperwork headache not you.
You can learn all you need about importing your car by spending a while on the CBP web site:
U.S. Residents Importing and Exporting Vehicles - CBP.gov
Personally I'd read the CBP web site (and the links), then call the port of import (where the car will come into the USA ...a list of their phone numbers is on the CBP web site) and talk to a US Customs agent to get all the answers I wanted. Then fly in and drive the car home.