The 30 Watt fan will cover an attic space up to 2,500 square feet, so once fan should provide plenty of circulation for your 2,300 square foot space.
The thermostat on the Remington Solar Attic Fan 30 - Watt is not adjustable.
It has a Humidistat and Thermostat that allow it to automatically fight moisture or heat based on its readings.
Yes. The Remington Solar Attic Fan (30 - Watt) will cover an attic space up to 2,500 square feet, so one fan would likely provide plenty of circulation for your 8x10 shed.