Well it's unfortunate that I can't modify individual FIDSI in that way, then, because having to modify them all at once rather defeats the purpose of what I was working on.

However, in regards to pop cap, modifying those numbers did not change anything; in fact, it would be quite problematic if they did, because at 14 pop slots, the pop wheel actually runs out of visual space for more slots and would begin overlapping with the first few slots. On the bright side, 14 is a much better number than it appeared to be in my head, and still works rather well for my purposes as long as nobody magically ends up with a system of all Large planets.

You can modify individual FIDSI, as while the PlanetInitalFIDSPenalty alters them all simultaneously you can have different variable names for each one.

<ModifierTargetProperty="PlanetInitialFood"    Operation="Percent"    Value="$(PlanetInitialFIDSPenalty)"  TooltipHidden="true"    />
<ModifierTargetProperty="PlanetInitialIndustry"    Operation="Percent"    Value="$(PlanetInitialFIDSPenalty)"  TooltipHidden="true"    />
<ModifierTargetProperty="PlanetInitialDust"    Operation="Percent"    Value="$(PlanetInitialFIDSPenalty)"  TooltipHidden="true"    />
<ModifierTargetProperty="PlanetInitialScience"    Operation="Percent"    Value="$(PlanetInitialFIDSPenalty)"  TooltipHidden="true"    />
<Modifier TargetProperty="PlanetInitialPrestige"    Operation="Percent"    Value="$(PlanetInitialFIDSPenalty)"  TooltipHidden="true"    />

You could have something like this:

<ModifierTargetProperty="PlanetInitialFood"    Operation="Percent"    Value="$(ModNamePlanetFoodBoost)"  TooltipHidden="true"    />
<ModifierTargetProperty="PlanetInitialIndustry"    Operation="Percent"    Value="$(ModNamePlanetIndustryBoost)"  TooltipHidden="true"    />
<ModifierTargetProperty="PlanetInitialDust"    Operation="Percent"    Value="$(ModNamePlanetDustBoost)"  TooltipHidden="true"    />
<ModifierTargetProperty="PlanetInitialScience"    Operation="Percent"    Value="$(ModNamePlanetScienceBoost)"  TooltipHidden="true"    />
<Modifier TargetProperty="PlanetInitialPrestige"    Operation="Percent"    Value="$(ModNamePlanetPrestigeBoost)"  TooltipHidden="true"    />

also In "\Public\Simulation\SimulationDescriptors[TechnologyEmpireDevelopment].xml" (Line 140) it shows how the PlanetInitalFIDSPenalty is set differently for each planet type 

<Modifier TargetProperty="PlanetInitialFIDSPenalty"Operation="Force" Value="0" Path="../ClassEmpire/ClassColonizedStarSystem/PlanetTypeSwamp" TooltipHidden="true"/>

In the System improvement definitions you could have something like:

<Modifier TargetProperty="PlanetInitialIndustry"Operation="Addition" Value="0.5" Path="./ClassColonizedStarSystem/PlanetTypeAtoll"/>

<Modifier TargetProperty="PlanetInitialDust"Operation="Addition" Value="0.75" Path="./ClassColonizedStarSystem/PlanetTypeIce"/>

This should boost atoll's industry by 50% (from 6 to 9) and Ice's dust by 75% (from 4 to 7)

I'm not too sure on the modifier path, this one "./ClassColonizedStarSystem/PlanetTypeIce" might cause the building to effect all ice planets empire wide, it might not but if it does try "./ClassColonizedStarSystem/ClassColonizedPlanet,PlanetTypeIce"