A lot of this was phrased like questions, so I figured I'd answer those questions to the best of my ability too.
More interactive worldgen maps and civs sounds cool, I would definitely like that. But man, is that going to be a long way off. We had a little map editing power built into the pre-steam version, like to set elevations, rain and drainage, savagery and even good/evil ranges IIRC. I never messed with it because I didn't like that it totally overwrote the random generation of all of those features, and the Perfect World utility does it so much easier with an actual HTML GUI and the ability to modify a map generated from randomly drawn heat maps. We might get that back at some point, and if we do, then we might get some new features. I imagine it got cut because it required extra GUI work.
The Perfect World utility hasn't been updated in years, but was still mostly-functional for the last pre-steam release version. Maybe someone will work on updating it/making a new one?
Personal beliefs come from religions and persuasive books written in world gen right now, as well as a bit of random variable manipulation on creature creation, so it isn't totally static. But local governments dont vary right now, it just depends on the personalities and beliefs of local leaders. It would be cool if they did have one or two values that differ from the civ, added by the founding members of the site government
Community members will have to work on writing up wiki documentation.
Racism isn't something the Adams brothers wanted to simulate too much. We're not going to see genocides but little disagreements and distrusts may be. Cultural biases towards members of foreign nations, depending on the relationships and histories between the nations, regardless of species of the individuals is something that's actually likely to get implemented. There's already religious purges and wars in worldgen history, too.
Slavery and classism might get further developed, but again, the Adams brothers dont really want to simulate all the horrors that real-world people visit upon each other. Things like poverty and homelessness and slavery in the abstract/statistical sense wouldnt be too graphic, and would lead to narratives like popular/slave revolts. We already have rulers "passing oppressive laws" to suppress rumors of their immortality. But I wouldn't get your hopes up on seeing during-play police/army brutality and slaves being beaten/tortured. Entire slave classes/social castes/races with heritability to children also isn't something we're likely to ever get. Indentured servitude or prison labor for criminals/debtors/prisoners of war are possible, and currently prisoners of war are the only prisoners you can encounter in adventure mode. But currently civs can allow slavery ethically, human civs do, but its not implemented in any way. Goblins kidnap children and see slavery as a "personal matter" but don't actually enslave anyone either, ignoring the part where the entire civ are kinda slaves to the demon lord/master. But even they could get murdered (which goblins do a lot of), and someone else (not necessarily their murderer) ends up being the new master.
The caste issue isnt solvable right now, no. Its been suggested to solve it in the past, by having almost all the kids be one of the parents' castes, and a much smaller than pop-ratio chance of one of the other castes being born instead.