hey111:
It's a turbine flow sensor prewired to a 3 pin plug. http://ly.rsdelivers.com/product/gems-sensors/173937-c-rs/turbine-flow-meter-g-3-8-1-10-l-min/4468292.aspxSo I'll need to look at a sensor shield & appropriate plugs then?
No, this is not one of those "learning kits". You have a hall effect rotometer which you are going to have two for power and the other one will be a signal in Hz. Check Gammon's frequency counter sketch...
... and I would go with the 2.2K pullup resistor.