Global cost of hurricanes will likely decline from 0.04% of GDP today to 0.02% in 2100.
I don't think that's correct, but that's also an odd thing to focus on. There's glaciers melting, ocean acidification, forest and peat fires, heatwaves in India, and various other things. I think we've already seen some significant rainfall pattern changes; nobody really knows how they'll end up, but things were set up based on existing ones, so change would generally cause some issues.
Climate-economic research shows that the total cost from untreated climate change is negative but moderate, likely equivalent to a 3.6% reduction in total GDP.
Nobody really knows.
The popular 2°C target, in contrast, is unrealistic and would leave the world more than $250 trillion worse off.
World CO2 emissions were ~37B tons last year. Complete mitigation would be ~$70/ton if done intelligently. That's ~$2.6T/year.
Marine cloud brightening is quite possibly worth doing, but the more of it you do the less cost-effective it is, and it obviously doesn't do anything about ocean acidification.