I like the Warhead factor being added. It is close to making an AOE and gives some credence to making larger AMM's and also giving some variety to strike packages. Throwing in a couple of "Frag Missiles" against ships in order to take out their potential decoys to give a follow up salvo a better chance of a hitting the actual ship target(s) both "feels" right as well as gives some interesting tactical consideration for missile warfare in general, putting an emphasis on multiple salvos versus just pure alpha strike potential.
On the Ranged Final Fire PD option, as I've stated elsewhere there should be no way to know what type of warheads an opponent is using, and thus having them fire "just before the warheads go off" does not make any real sense. However, one would know what one's own capabilities are, and thus having one's PD Ranged Final Fire engagement range to be tied to the Laser Warhead Range technology would make perfect sense. This will give a short term boost to the one's who advance the technology first, while creating the realistic offense v defense "arms race" which has always occured.
Laser Warhead Range should MAX at 1 light second or 300k if we are going to round, the BFC's to align to a target in a small package like a missile simply do not have the computation power to predict any further than that. We do not need missiles with fully functional (ranged) lasers on them at all.