Yes. Any minimally processed vegetable should be refrigerated.
It's still a living plant. It does best if loose wrapped so it stays moist but can still breathe.
Lettuce retains quality and nutrition best if kept refrigerated. Minimally processed lettuce should be treated like any other potentially hazardous food and should be kept refrigerated.
No. It does not.
Cardboard boxes by truck or rail, refrigerated containers
Yes you will need to refrigerate after opening, but it doesn't need to be refrigerated if still sealed.
Sterile water does not have to be refrigerated. However, to remain sterile, it must be kept in a clean, sealed container.
Warm temperatures allow certain bacteria to multiply very fast. It depends what kind of bacteria are on the iceberg lettuce as to whether or not it would be dangerous. If the lettuce has been contaminated with pathogens, it could be dangerous whether or not it has been refrigerated.
In a sealed, refrigerated container, you could store it for months.
It's supposed to be served chilled, so yes.
Yes, lettuce can be left out at room temperature but this will make it go bad faster if it is not kept in a sealed bag. Although lettuce goes bad pretty quickly anyway, in the fridge or not.
No. Vacuum seals keep out air, so the bacteria cannot grow.
Yes, it will wilt without keeping cool.
You can keep lettuce vacuum-sealed in the freezer because you will break the cellular structure that makes it crispy. But you can freeze tomatoes and use it for tomato sauce later.