Yes to all of this!
My biggest trick for overcoming imposter syndrome is forcing myself to be honest and open when I don’t know something. At first saying “I don’t know” feels uncomfortable (especially when you’re the boss), but it gets easier.
It turns out that no one knows everything (even the people who seem really, really clever and together!) and by being honest about my own shortcomings, it helps others be honest too. Building a culture where asking questions is encouraged and where it’s safe to admit imperfection is the best defense I’ve found for battling impostor syndrome, and the best way I know to learn from the smart people around me.