In a small hall, the band may not need a sound system. Use the best sound system you can afford. There is lots of variation between sound system components, especially mikes and speakers. If you are assembling your own system, take time to try out different components, if they are available to you. Plan for a system with monitor speakers.
Monitors help the band hear itself and stay together.
Get to the dance in plenty of time to do a sound check. Take time to get the monitor mix right first. Usually the caller is left out of the monitor so the band can focus on its sound. Have someone check the band balance in the hall, and the balance between the band and the caller. Some callers like to shout into the mike.