Yes, and substitution of boiled for boiling water has produced many terrible cups of tea.

It depends on the tea, but some cannot be well made with a metal pot of water that's taken a few minutes to get from the kettle to the table.

Arguably it depends more on the atmospheric pressure to get boiling water as close as possible to 100°C.

The general rule of thumb is that black tea (i.e. fermented tea leaves) should be brewed at 100°C, green tea (non-fermented tea leaves) should be brewed around 80°C to avoid it being bitter and white tea (young, non-fermented tea leaves) is best at around 70°C.