Try to get good GMAT score, so you will have a better chance to get in a good University. Once you are accepted in a good university, then it will be easy to get a Visa.
Pakman
Look for details, what you had to do for this job. And if you are confident doing this job, go for it. Is there any contract you had to sign and for how many years.
There are few Law firms, who can organize this kind of Visa. They need your complete documents and they have to see your past experience. The law keeps on changing.
CAN gave you visa to enter the country. Relax, Whatever happened with your US visa is the past. Just explain clearly, your purpose of visit at the port of entry.