Hi and welcome.
I am just gonna assume you are already set on the BH, which is a great PU, but should you have any doubts please tell, weŽd gladly help out (and probably confuse the heck outa you xD).
Firstly, the alnico ceramic choice is never there for the neck. Infact all necks but one (the painkiller) are alnico.
As for the bridge think about this: Alnico is warmer, more organic, little more growl in the mids
ceramic is tighter, smoother in the mids, more cutting in the highs
For all out metal ceramic tends to be the better option, but alnico delivers more versatility and you should never think that it is not tight enough or such.
Oh, and of course:
http://youtu.be/2qacdnnbe2kLastly, when you get the BH set be sure to install a splitting posibility, well worth it with that PU.