Here's what I know:
Baby Girl with Bizarre isn't really featured Eminem, it's just a sample from Hailie's song at the chorus.
Countdown isn't a song, it's just Em saying: 10, 9, 8, 7 etc.
Defence is the Outro from Obie's Cheers.
Detroit grammar isn't a Nelly diss, it's Nuttin' to do with a different title.
Showdown is "Bad guys always die".
Thug love isn't real, it's an actually fucked up remix, with the accapella of an old Em freestyle.
Murder she wrote is a remix version of "murder murder" off Slim Shady EP
Flawless Victory is just "Serious" with a different name. (I'm not sure, but 90%)
I'm Marshall isn't a Canibus diss, it's just Eminem's verse, from "JD Diss" which originally featured Xzibit too. (also called "Grindin'" by some sources)
I'm a playa remix isn't official.
The N Bomb doesn't seem to official to me, but maybe it is. Judge for yourself:
http://www.youtube.com/watch?v=swE-f1xjITMDrastic Mesaures is real, but it's hella old, and the quality is very poor.
Fuck you (lab dat remix) if a remix with an old acapella from his early singles (can't remember exactly which one) and with the beat of Dre's "Fuck you" off 2001.
Ludacris & Lil wayne diss, isn't EM, it's just some fake ass guy tryna get attention by postin this song all over the internet, like it was Em's shit...
hope that helps

There will be my signature. It'll be a hot one. You'll look at it and say - wow that's a gangsta signature.