In regards to your first question, the word you're looking for in google-able energy industry jargon is "dispatchable". And yes, dispatchability of intermittent generation is achieved in a couple of ways in contemporary electricity networks:

  1. Deliberately backing off wind or solar generation from full capacity to provide reserves for demand spikes, transmission/generator outages, etc.  This means other generation that may otherwise not have generated at all over that period, is brought online to cover the shortfall.

  2. Co-locating grid-scale batteries at intermittent generation sites ("hybrid generation facilities" in energy industry jargon) to cover short-term contingency events.