and the reason he (even still) cannot physically harm people
This point still confuses me. He quite handily puts Kelsier on his rear in The Well.
So he can harm someone if he's provoked? Or is it because he knows that regardless of what he does to Kelsier it won't actually harm him?
And a lot of "harm" is in the mind. Even without a corporeal body, it would still register as pain, thus harm?
And wouldn't it still be considered physical harm, if Hoid was there physically? Applying physical harm?
If you re-read that scene, Hoid himself is shocked he's able to do what he does there. Let's just say he himself doesn't quite understand the issue as much as he once assumed.
Can we assume he cannot harm a LIVING being, but Kelsier is at that point not a living being?
This is the conclusion Hoid came to, so it's a pretty solid assumption.