Quoted from JOESCHALL:(1) Is this a true chip swap or is the 6264 to be installed into an open socket?
It's a true swap -- remove 6264 RAM and install the NVRAM in its place.
Quoted from JOESCHALL:(2) The manual shows a chip U212 with the number 6264\MS62256 on the CPU/sound board located right next to the batteries. Assuming this is a chip swap, is this the chip that I pull?
Yep, that's the chip. 6264 RAM is at position U212 (see diagram @ https://www.pinitech.com/product_images/ram_locations/ramloc_whitestar.jpg).
Quoted from JOESCHALL:(3) Does orientation of the new NVRAM chip matter (i.e., is there a top/bottom or left/right), or can it be installed without concern for orientation?
Orientation is critical. Make sure you pay attention to how the notch is oriented on the original RAM before you take it out. It should be facing down on your MPU, but just verify that. Then match the notch the same way on the NVRAM. Most NVRAM is going to have a notch designation (silkscreen or physical notch) or at least a pin #1 marking on it. Definitely worth verifying if you're unsure because if you power on with it in backwards it'll blow the chip immediately. So if in-doubt, post a picture to verify 
Quoted from JOESCHALL:(4) Once the chip is installed, should I just remove the AA batteries and leave the empty case in place?
Remove the batteries for sure. Some people remove the battery holder, but not necessary unless there was battery leakage that happened and needs to be cleaned up. If no battery damage you can leave it as-is, or some people add a note/label that nvram is installed and no batteries are needed (especially if machine is being sold).
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NVRAM, Bally/Stern LED Displays & Mods for pinball machines
