Are non-unibody MacBook Pros (Late 2006 ~ Early 2008) capable of Lion's 3 and 4 finger multi-touch gestures?
No - that era of hardware is a solid-state trackpad, not a multitouch trackpad and can only track one motion. Although it can guess fairly well if it's one finger or two that is moving in two dimensions (left-right and up-down), but that's all the hardware can tell.
Put another way, yours tracks the center of all touch points combined, not several touches individually at the same time with their own motion.
Yes - but only the very late ones, like 2008ish - at least my early 2008 MBP (last non-uniboby) supported all kinds of multi-touch gestures using bettertouchtool - didn't try Lion on it but in the last Snowleopard versions all the OS X multi-touch gestures also worked.