I don't think you need the beater, but we always seem to have one around, don't we?
I think that's a pretty comprehensive list of a bare minimum that studio guys might want to have with them. However, most of us aren't studio guys and don't need the depth. For example, I've played one gig in 5 years that I thought required a 5-string, and when I got there, they asked me not to bother with the 5-string because the writer of the chart didn't know what he was doing. And there was one time in my life I was ever asked about fretless, I said I didn't have one but I would play it if they rented me one, and they said fretted would be fine