I will try the the 10 and 15k resistors and take a look at the voltage.
The intent of the 330ohm resistor was to replicate the "pull down down" resistor from other Arduino tutorials (image).
"If you disconnect the digital i/o pin from everything, the LED may blink erratically. This is because the input is "floating" - that is, it will randomly return either HIGH or LOW. That's why you need a pull-up or pull-down resistor in the circuit." ("http://www.arduino.cc/en/Tutorial/Button")
Looking at the schematic, do you still think 330ohm resistor is useless in this role?
Are you saying that running a jumper wire from the negative on the 9.6V battery to the USB ground is a good idea? Shouldn't the 3.6 to 4.4 volts from the voltage divider flow to the ground present on the USB?
So I can replicate the work, what equation were you using to get 3.6 and 4.4?