The expiration date of your visa is the last day you may use the visa to enter the United States. It does not indicate how long you may stay in the United States. Your stay is determined by the Department of Homeland Security at your port of entry.
In some circumstances, a person may be released from custody without bail and be given an order to appear, with certain conditions as governed and directed by a court-affiliated agency. Project Remand ('PR'), a Ramsey County pre-trial court service program, is one example of such an agency.
A bonds make much more sense than posting cash bail. Common titles for the professional acting on behalf of the surety companies are bonding agents, who legally must be licensed by the state insurance regulatory authority (in California it is the Department of Insurance).