Some noob questions about PoS

Hello everybody, sorry about these noob questions, I’m trying to understand PoS and no article I had read explained it.

In PoS in general and on Waves, what happens if a node is selected to process next block and then it crashes or goes offline and doesn’t build that block? Is that block’s timestamp just skipped and next selected node processes a double-sized block?

And what do all other nodes do when they aren’t selected? Do they stay idle and saving electricity?

How much time takes each block to be created on Waves?