Why wouldn't price fluctuations influence consumer behavior? Electricity is purchased in bulk in Nord Pool whose prices fluctuate by the hour. Consumers, who account for 58% of production, certainly regulate their consumption based on prices. Even industries do and there have been several high-profile examples of paper mills reducing their production due to high electricity costs. Wind availability and temperature is what determines electricity prices, neither of which is particularly hard to predict.

Regarding your second point, this is handled via imports and exports and standby capacity. The Nordic power grid is getting denser which reduces the chances of catastrophic failure. While the Swedish right-wing press has predicted brownouts and "electricity ransoning" ever since the right-wing party made more nuclear part of their election platform back in 2020 (what a coincidence...), those dire predictions has not come true.