Crown vics are a completely different car from a Mustang. The spindles wont swap over. As for the rear it probably has a completely different rear suspension setup than a mustang. I wouldnt waste any time with a Crown Vic if I were you.
depends on the year, I believe '90-'91 models were mass air, ('92 is the debut year for the 4.6) but the computer was not exactly what you'd call for performance use...and tweecer doesn't have any profiles available for it...
if you're looking to do a basic FI swap, it would work fine for a daily driven low horse app though...