No, emissive armor is not a "blanket" protection for your ship. It only protects itself. Damage distribution is random. The only control on damage distribution is 'armor' or 'not armor'. While you have armor, damage is distributed randomly among armor components - except when a weapon that skips armor is being used. When armor is gone or an armor ignoring weapon is being used, damage is distributed randomly among non-armor components. So, mixing emissive and standard armor is likely to result in a lot of your standard armor getting destroyed just like it would without any emissive armor.
I would point out, though, that what you described is an interesting concept that might be added as a special component. It's what I would call a "damper field" and would make a fascinating alternative to shields. If all direct-fire weapons firing on your ship were reduced by say 25 percent off the top, AND you had good emissive armor, would you need shields?
If you have good weapons yourself, the other guy could be toasted long before your armor is gone. Ever play Master of Orion II and tangle with the Antareans? They had damper fields on their ships.
[This message has been edited by Baron Munchausen (edited 26 September 2000).]