I need to run underground water lines to my gardens 250'-300' from my house. I would like to be able to hook-up a hose at the end and possibly be able to drink from a faucet. What type of hose would you recommend? I will also need to drain the pipe in the fall because the winter temperatures will fall below a minus 20 degrees Fahrenheit.

What type of pipe would you recommend?
Go with a 1" PVC schedule #40 supply to the garden. At the pump end install a stop and waste valve, (see image). To winterize the line simply open up a faucet on the other end and the stop and waste valve and drain the line. At the end install a shut off valse then a tee. You may now pipe off that tee for a hose connection on the end and as faucet off the branch.

Important! When you install the PVC service line give it back slope to then stop and waste valve so it can be drained for the winter.
Good luck, Tom