None of these feel particularly true to me, but in particular "less code is more readable" is just so clearly not true. If this was the case we'd all still be using Perl.
In terms of developer productivity, less code faster to write and faster to read. To a point. The sweet spot is the shortest code that's still easy to read & write.
However "less conceptually complex code is often easier to reason about' is absolutely true and it takes most people a fair amount of practice (and at least if you're me, a lot of wondering why your foot suddenly has a hole in it) to properly appreciate the difference between "less conceptually complex" and "less".