question on T&G flooring

[carbonebria]

I am planning on installing 2x6 spruce tongue and groove flooring on PT 6x6 beams for a 25' yurt in central VT in coming weekend and I was wondering what the preferred method to secure the 2x6 T&G to the beams would be? Nails or screws? And do people rent a nail gun of some sorts?

My second question is, does it make sense to first staple down a vapor barrier of some kind of plastic to the beams first before laying down the T&G?

Thanks in advance,
Brian