At a probable cause hearing the court will look to determine if the District Attorney has probable cause to proceed with the charged offense.
To find out what the DA has your husband should first consult an attorney. If he cannot afford one he shoudl ask for a public defender. They draft an informal request for discovery, where the DA will have to show all the evidence he plans to use and all the witnesses he plans to call.
His prior record will only be introduced if he chooses to testify in court.
At the hearing the DA needs to present live witness testimony to the Court, they need to present enough evidence to show that probable cause exists for each of the crimes. If the victim witness does not appear for the hearing it is possible the case could be dismissed. It is also possible the DA may be able to offer evidence through another witness. Without knowing more about the facts of the case it is hard to say.
Typically in my experience in the Leominster District Court and Worcester County in general the DA's office will avoid a probable cause hearing by directly indicting the Defendant. That way the defense attorney does not get to cross examine any witnesses at the probable cause hearing and the case gets transferred to Superior Court. So chances are there will be no probable cause hearing.