The "Butterknife" was just a colloquial name for a particular milling pattern.
You can find a manual here: http://www.angelowners.com/showthrea...-(PDF-and-HTML
Intellifeed is a system to activate and power an agitating loader using the circuit board inside the gun. You can also use it with newer loaders to activate the motor, but not to power it.
In order to use 9 volt batteries you would need to upgrade your board. Currently the only board available for Angels at retail is the Virtue board, and it costs about as much as the gun itself is worth. However, 7th Element is working on an Angel board that should be priced at about half, or if you wanted to go the DIY route you could install a Universal T Board or PMR board (the latter is very inexpensive and was gaining popularity as an alternative for the LCDs. See here
). You may also be interested in the CR123A mod that replaced the stock NiMH battery with disposable camera batteries: http://www.angelowners.com/showthrea...able-batteries
You would need a Datalink cable/kit to interface with the gun on your computer. They are difficult to find used, but you can build a DIY one. Unless you've got a locked board, I would generally say it's not really worth it, but here's some info: http://www.angelowners.com/showthrea...-Own-Data-Link
Check out the Ultimate Sticky for more good info. Check out the Lube Thread for a maintenance guide. Between that and the manual you should be pretty well covered.