On point 3, 50% is very high for slashing and might have unintended consequences for most operators. I propose we only slash offline nodes to begin with (0% votes) and lift it up over time.
For example, a lot of my vnodes are still syncing shard blocks during the first committee as ~4h is not enough time to sync everything from pending->earning, so sometimes the vote is under 50%. 2nd/3rd committee goes back to 100% votes as the shard is fully synced.