Seems like you pretty much have a handle on things to me.
Yes, you'll need to supply and adjustable negative voltage. A resistive divider is the easiest way to provide the adjustment, and yes, the centre pin is connected to Vo. You well on your way..
A DC-DC converter will give you your negative voltage and you only need the smallest one you can find. If you are connecting the display INside a computer case, there is also the option of utilising the -12V rail of the PSU, however I suggest you use a fixed resistor in series with your POT (20% of the value of the POT, ie; if POT is 10K use a 2K resistor between one end of the pot, and the -12V rail).
Hmm thats given you alot of options....
The font select pin selects the font to use in the internal character rom, what the link you provided doen't explain is what is what with it... So, either tie it hogh, or low, and see what happens. It isn't going to harm the display if it's wrong, but it might display incorrectly if the larger font size is selected.
Anyway, hope that help. Have fun getting it going.
