To what extent?

A few items to mull over and discuss. This could rightly go in the real science forum, but since I want to collect insights and opinions, I figure down here is as good a place as any.

Do we have to see something to accept it with reasonable certainty as a fact - at least tentatively?

Do we have to be able to conduct reproducible experiments to consider something science?

Do those experiments have to be in a controlled lab situation?

What are the requirements to call something an experiment?