Second. Even if you knew two days ahead about wind speed fluctuations that lasted for 10 to 20 minutes. What, then? You can't inform the population there will be 10 minute outages, in advance, or ask them to turn off appliances for exactly 10 minutes, in advance.
Solar and wind aren't reliable. The plan is to turn on thermal plants when the wind stops blowing. In my very humble opinion, solar and wind aren't THE long term future of energy production. They have their uses, but the way it is being marketed obeys to political discourse, not reality.
You can. And there is companies specialized in that for the Wind and solar industry. [1]
The reason is pretty simple: Weather variability tend to be high at the local level but pretty predictable at the national level (the energy grid level).
And to answer to the original post, yes Nuclear energy can also be fine grained controlled to compensate the renewable energy intermittency. It is done every day in France. It can be done yes, Is it efficient ? Not really.
No they don’t. Wind and solar energy output can be very well predicted for hours and days ahead.