1. The only way to use it with missiles would be some form of command
guidance. I needn't say what would happen to that transmitter.


Every semi active radar guided missile system is an inherently bi-static system
and if get close enough to target even small missile antennas could pick up
returns.
Active homers need only an command link to put them in close vicinity of
target.

2. With SDB you can hit *many* targets in one pass. With the wing
kit on them they have a range in the 30 to 50 mile range.

30-50 m range is not bad but pretty useless aganist 500-600 miles multistatic
tracking and detection ability ,specially if your opponent has fighters with
good range and long range SAMs.

3. About the best way I can think of would be to use the imaginary
radar system to find the x,y,z coordinate of the aircraft, fire off a
FAST surface-to-air missile that has a good IIR seeker. Send periodic
updates to the missile until it's close enough to see the target.

You are on right track but anyway if you come close enough to target any
receiver could pick up echoes or any active homer can lock on even if the
receiver or active homer is inside frontal threat cone.

The weak links I see are the transmitter that sends the update though
they could make it so 99.9% of the time it's off the air except for
when you're making sure the missile has the right target, but even
then we're talking seconds. Also

Right,generally multistatics are more vulnerable to some forms ECM than
backscatterers,even without considereng missile datalinks.
But if you rely on active ECM instead of passive stealth for penetration ,thats
a totally different ballgame again.