On the free call question, most facilities allow a phone call shortly after booking, typically within the first couple of hours of arrival. Whether that call is actually free varies by facility. Some provide one free call as standard practice. Others allow the call but run it through the facility's phone carrier, which means it comes at the regular rate and someone on the receiving end needs to have an account set up to accept it. Do not assume it will be free, and if possible make sure your account with the facility's carrier is active so her call can go through without a problem.
On how long she will be there, that is a question with no honest answer without knowing what she is being held on. Hillsboro is the county seat of Jefferson County, so she is likely at the Jefferson County jail. How long someone stays there depends entirely on the charges, whether bail has been set and whether it can be met, whether there are holds from other jurisdictions, and how the court calendar is moving.
If bail has been set and it is within reach, a bondsman can often get someone out within hours of the bond being posted. If bail was denied or set at a level that is not manageable, she will remain there until her case moves through the court process, which could be weeks or months depending on the complexity of the charges and the court's schedule.
The first step is finding out exactly what she is charged with and what the bail situation looks like. That information is available through the Jefferson County court clerk or the jail's booking information line.