DDR3 SDRAM

http://en.wikipedia.org/wiki/DDR3_SDRAM should answer your 2nd question.

I suppose as long as it's 240 pins, it doesn't matter where that hole is.

EDIT: So basically, while the DDR3 reads/writes twice as much as the DDR2 per access to the memory, the time it takes to complete that access is also significantly higher (almost double the timings of DDR2), resulting in a similar throughput performance?