|Todd Stewart Contributor|
1)Are there mortal civilizations on all of the outer planes?
2)How do the outsiders of Heaven interact with the mortals that live on the plane of Heaven?
3)How much do you know of the Empyreal Lords?
1) Populations, yes. Civilizations, no. I see long-term habitation on any of the outer planes not necessarily being good for a mortal. Be it horrific of beatific, exposure to those environments before you're ready for them will radically alter your outlook on things afterwards. I suspect that to an extent, the planes themselves may alter their own appearance to better accommodate mortals; altering their perceptions and experiences and modulating the intensity of what they experience compared to an outsider.
You see some very clear signs of this in James Sutter's excellent novel 'The Redemption Engine'.
2) Warily I suspect, with those mortals simply not being capable of accessing much of the plane since they're not considered ready for it. Every interaction won't be by chance, and ideally they'll all function to mold and influence that mortal's moral/ethical/alignment towards Heaven's goals (though ultimately it being a case of free will on the mortal's part).
3) A good amount, but I'm not the expert here. Between when I wrote 'The Great Beyond' and when 'Chronicle of the Righteous' came out, the concept of some of the good outsider races evolved and many new Empyreal lords came onto the scene (the name didn't yet exist when I wrote TGB). Some of the celestial paragons I came up with didn't feature in CotR at all (Melek Taus, most of the agathion specific ones, etc), while others were greatly expanded, and some really awesome new ones were created. That's how shared world writing works :)
I've never been super fascinated by celestials though, unless you're talking about celestials that used to be fiends or fiends that used to be celestials. I like edge cases. Most of my adoration for planar creatures resides with proteans, daemons, and axiomites (and jyoti and sceaduinar). Those are my favorites. Of course I'd never say no to writing on any sort of planar concept. But celestials are a weaker point in my repertoire.