Sorry for late answer. Maybe also add ability to list all ops?

I thought that wouldn't be necessary as the /deop command suggests the operators (and /op suggests the non-operators), however only the owner (and operators with level 3 or higher) can use these. Should normal players be able to find out who is and isn't an operator (an indicator in the /list command perhaps)? They can't in a Vanilla dedicated server.

I think nope. But I think that's better to have more obvious way to get ops list (maybe even just /op command or /ops). "Simple is better than complex", but anyway it's up to you.