Most likely saying that his beats shake like waco, since Waco, TX has the Balcones Fault to it's North. It may also be a double entendre, referring also to the Waco incident linking it to Quake the videogame.
In reference to the id Software release "Quake" (1996); the line implies that the person in question has the aptitude greater than or equal to that of the Waco Kid's (Billy the Kid) firing abilities, in that they can quickly approach, defeat, and move on.
andre the giant is a reference to andre, a rapper in the song itself. mister elephant tusk is a description of andre, showing how famous and expensive he is. (elephant = big star) (tusk = ivory = valuable)
he's not talking about horses. his "stable" is actually his garage. after getting in an accident, Dr. Dre will just get another car. cars became common transportation after horses, and so their power is still measured in units of horsepower.
this command of extreme disrespect stems from a joke where you ask someone if they would like some "fromunda cheese" - they of course will not know what it is, and you reply "cheese from unda my nuts!" (supposedly funny)