Modern reactors can run on the spent fuel of older generation reactors. The waste issue isn't as big of a deal as it was a few decades ago.

Nuclear is a great energy source. My state (Illinois) generates over half of all its energy from nuclear. France is a great example of a country that maximizes the potential of nuclear energy. The waste is not a problem if it's stored properly. The much bigger problem are carbon/methane emissions which are fucking our climate right now. Also, nuclear waste can be reprocessed to make it less volatile and radiotoxic, but that requires an advanced application of technology.

Batteries and solar absolutely yes, we need to be scaling up battery technology as fast as possible, particularly sodium-ion batteries for static energy storage from solar power. The biggest problems with wind/solar is the actual storage of the energy. No wind? No power. No sun? No power. That's why you need batteries, and battery technology has only gotten good enough in the past couple years.

Scaling up hydrogen is very difficult, it's extremely volatile, and can realistically only be used in large scale power plants because transporting hydrogen is extremely expensive. Fusion could be good, but it's still being worked on, and who knows how long it'll really take for us to have a practical implementation.

They're expensive to build because we don't build enough of them.