"and spreading out as human populations do"
I'm not sure if populations are "spreading out" much these days. Most population trends are toward urbanization: people leaving the countryside to move into big cities. Additionally, forecasts predict a contraction of the human population in the near future.
"is there any benefit to warming that the earth could adapt to. IE, more land mass for expansion and agriculture, better access to more resources, etc. Short of inconvenience for the poor and the rich who line the shores."
It's not just poor and rich. Most civilizations throughout time have settled near water for obvious reasons. Even today, around a quarter of all people live near ocean coasts.
As for benefits of climate change, if there are any, they will be overwhelmingly buried in the mountain of ill effects climate change will have. e.g. Even if we somehow got more cropland from it, crops might not grow if the temperature and weather isn't amenable to it.
"AND, if the earth warms up, doesn't that increase evaporation of water to move it back into the atmosphere and still collect at the polar caps"
Evidently not, considering they're melting at an increasing pace. Also, I don't know if water vapor automatically travels to the poles. It likely has more to do with overall atmospheric circulation patterns, as well as temperature and other factors.
"Does that offer any help between the two of evaporation and atmospheric cooling that could be assisted by the increased atmospheric water content as a thermal conductor?"
Not sure I understood this part.
"Just curious from a "what if we can't really do anything short of being insanely monstrously radical humans wiping other humans out" perspective."
I don't buy into the "kill everyone to save everyone" perspective. I usually tell people who endorse it to start "at home" if they think that. Personally, I think we absolutely *can* solve climate change without genocide (jfc), but the problem is that it will require some personal sacrifices and evidently most people aren't ready for that. But if we're going to take a hardline approach, I'd infinitely support strong policies that are unpopular to lower emissions rather than to start killing people.
"These are sincere questions. It truly is from the "what if it's too late" perspective. How do we adapt in spite of the changes? Are we smart enough to do so? And are there any benefits at all?"
It might be too late in that we're not making the changes we need fast enough to avoid disaster.
As for climate adaptation, there are lots of interesting websites and blogs that look at mitigation and adaptation methods.
And of course there's a benefit in trying to fight off mass death, even if we can't save the planet to the extent that we'd like.