Guided tour documents: what do I actually need to print, if anything?

Tour is in 3 weeks (Iceland) and I just realized I have no idea if I need to print anything. The booking confirmation is in my email, and I have a voucher number. Is that enough or should I be printing physical copies?

Also, what documents should I bring besides my passport? Do I need copies of travel insurance, vaccination records, the actual tour itinerary? I’m old school enough to want a paper backup but also don’t want to carry a filing cabinet in my day bag.