There are a few more factors that will determine what will happen. What were you convicted of or which charge did you plead guilty to? How long have you been on probation? Are there any other conditions of your sentence still outstanding? If you do not possess a motorcycle or have been too injured to ride one, not doing the MSF class will not be a problem. If the judge insists on completion of that, there are other car related driving classes you can complete. I have never seen anyone sentenced to jail for failing to pay restitution in their case unless they refuse to do so at all. Your probation will most likely be revoked and re-granted for an additional period with the same conditions. If there already is a bench warrant for your arrest currently, you will probably be taken into custody, but if you merely received a letter stating your probation may be revoked and a hearing will be set, then there is probably not a warrant for your arrest currently unless you have several different cases.
Great response by Mr. Greenwood. I would hire an attorney back in the jurisdiction where you have the warrant to see if the attorney can negotiate with the DA and with the judge to resolve this by mail. You say that you can't afford an attorney. However, this is simply a case in which you can not afford to proceed WITHOUT an attorney. If your future and your security clearance have any value to you, you will borrow money from family or get a loan or charge the small retainer on your credit card. It is well worth it.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.