Such a pleasure to find that my personal project being discussed on Arduino forum!
I guess it is already too late and not topical but nevertheless I'll try to address some of your questions:
In order to control VFD display you need only:
1. VCC - +5V rail,
2. Data In - serial data input,
3. CLK - serial data clock.
4. And Ground of course.
No need to use:
1. Data Out if there is no requirement to read VFD controller's RAM - it is not vital for displaying characters on VFD display,
2. STB is already connected to an external oscillator on the same PCB, you don't have to connect it to anything else.
A link to an example of working code for HT16512 is here: http://code.google.com/p/magicclock/source/browse/trunk/CPP/HT16512.cpp
TORPO 6312 is almost the same as HT16512 so the code should provide you with general understanding. However, the code contains charset for 16-segment display and looks like you have 7-segment and the number of digits is different - some changes still have to be done.