It seems to me like the other two comics are meant to be funny though, so the icons being lighter and more inviting makes sense.
I think more people on the site do gravitate to brighter icons, but since your comic itself is serious, the people who click friendly looking icons might not subscribe after actually reading the comic and seeing it's more serious. Less people might click on the darker icon, but at least you know the people who do will be genuinely interested as that's the kind of comic they're looking for and what they expected when they clicked the icon.
As for the color of the uniform, I think yeah you might be over thinking it. The skin is definitely a different color from the uniform and it's clear which parts are which even at a glance.