Wow... umm... LSD's are difficult to spot, because they're completely in the transmission... one way to check (And this is by far one of the dumbest ideas I've ever had, but it will work) would be to go to a parking lot where there's some gravel and concrete next to each other... position your tires so one's on the concrete and one's on the gravel, and give it some gas... if the one on the gravel spins like mad, then you don't have a LSD... if it spins, then the tire on the pavement grips, then you have one.
The whole tranny-welding thing he did was to eliminate wheel hop (Quarter mile stuff), but what he did was an absolute ghetto route that's IMO really stupid when he could have gone with cheap urethane bushings...
Forgot how to tell the year on the serial number on the engine.
j-spec=jdm, and I can't give a definate answer on this too (Don't know too much about B18a)
ripped CV boot = bad, but it's less of a squeal and more of a rapid click than anything, and should happen most around acceleration and turning... I'd check the brake IMO
Send us a pic of your engine bay and we'll direct you about the vacuum lines