Before you get into this project much farther, I think you should do some reading. The size of the pipe is critical and if you want satisfactory water flow and pressure, you need to know how to calculate that correctly.
The pressure, type of material the pipe is made of, the elevation from the point you feed from to the point a 1/2 mile away, the water temperture and number and type of fittings etc. all play a part. Then when you get to the building, you have a number of factors to figure in using the same as above again.
Actually you start at the building by determining how much water you need at what pressure and work toward the water source. Here are a few URLs as a start.
I suggest 200 psi rated polyethylene tubing with as few fittings as possible; none other than one on each end being the best. You can get up to 5000′ (continous) rolls.
Quality Water Associates