Maximizing the life of the tiny LiPos ???

For Li-Polys, the consensus seems to be to store packs at about 85% of peak. That works out to about 3.85V per cell.

(1) I seem to recall that all the stuff that I read said 50% charge, perhaps I am remembering incorrectly. (2) What is the best way to determine the voltage of the little tiny 70-150 mAh batteries?

With a volt meter. But 1/2 voltage isn't 1/2 charged -- 1/2 charged means that you've sucked out half of the total amp-hours that the thing can hold. Pull a LiPo down to 1/2 voltage and it's toast.

Where do I get a voltmeter that will work with the tiny little cells?

Your confusion confuses me. Any old voltmeter will do, as long as you can get their probe tips on the wires.

Try Radio Shack.

I was able to make an adaptor for my Watts Up watt meter. It seems to work very well when the battery is fully charged. When the battery is nearing its cut-off the LCD display gets dim.

What is the recommended minimum voltage for these LiPos to maximize their lifetime?

Y'know, I'm drawing a complete blank. Battery chemistry is battery chemistry though, the voltage is invariant to size -- currents and capacity scales with size, but the voltage is a consequence of the chemistry which does not change. So whatever is recommended for regular LiPo cells is what you want to follow for the teeny ones.

I will guess that 3.66 volts is reasonable, and conservative. I am pretty sure that this was the most conservative number that I have encountered.