[quinthar]

Unfortunately you can't add new nodes without reconfiguring the cluster, and currently that requires restarting each server (though so long as you don't do it all at once, server restarts are normal maintenance that causes no downtime to the end user). This could likely be added without too much effort, but also the real-world use case of this is uncertain.

The consensus algorithm is only used to elect a master -- once the master is identified, it coordinates all the distributed transactions. If the master dies, everyone who remains elects a new master and re-escalates all unprocessed write transactions to the new master.

Read transactions are processed locally by each node, so only writes need to be escalated.