How Stuff works is an excellent resource for questions like this -
http://science.howstuffworks.com/tr...train1.htm As for could it be used for a car or more correctly an individual transport vehicle, the basic answer is yes. A numbers of systems have been proposed that have have that basic characteristic.
On your third question I am not sure I understand your specific question. Maglev trains require use electromagnets.
Niel Leon
engineering.com