Do you have a defense? Can the State prove the charge? Have you been doing fabulous on probation? No one can answer this with out all the information about both of the cases but you are in a very tough position.
Yes you should hire an attorney - an attorney could investigate the facts of your situation and let you know if you have a defense to the new charge. If you have done all the things on probation you are supposed to do, this would also put you in a better position for your lawyer to argue for you to remain on probation. Your situation may appear daunting, but you can only put yourself in the best position to face the situation by hiring a good defense attorney.
yes, absolutely if the facts are in your favor.
Providing general answers are meant to help the poster to understand some complex legal concepts and in no way creates an attorney-client relationship.