I don't have experience of this as a parent, but as a teacher of young children.
I'm not sure about myths but I don't think you need to worry about sheets and hairbrushes. Live nits don't live long away from heads, and the eggs are attached very securely to hairs.
I would say that you need to keep wet conditioner combing and checking every other day over the next few weeks because if you missed just one egg, it will hatch, probably without anyone noticing, and will be laying more eggs with 10 days, then in 2 weeks time from then you will have another infestation.
It's a PITA, but the wet combing does work, you just have to keep doing it. HTH
the headlice can survive up to 24h away from the scalp, so check coats, hats etc.
i would wash hairbrushes and make sure your DS has a seperate one. i always use seperate towels too from DD for drying our hair.