[Val]

As to WPs, I'm still thinking towards my intial idea:
WP can only take out fighters and provide armor for defense - as bunkers (SJ is credited with this idea, at least I think it was him who suggested it). Then you have to rely on Sats, ships and bases for your defense. Which is pretty consistant with all the B5 material I have seen or read (other than that one episode that Nomor had quoted).

In almost everthing I have seen, the only thing they talk about that is on the planet is the control stations for the satellites and military instalations (bunkers, fortresses, etc).

I would put in the PD weapons to shoot down fighters and incoming missiles, but even Earth (the crown jewel of humanity) only had a satellite defense grid and supplemented it with ships in orbit. If anyone saw the tv-movie where the Drakh unleashed the nano-virus, those tankers that made it past the defense grid had no trouble in the atmosphere (other than being shot by ships in orbit and fighters).

The only exception would be the Great Machine, which would be a MASSIVE planetary gun that would take most cargo space on any planet and would be limited in shots. Though the hits would be guaranteed kills on just about anything.