I would have them sign the releases at the taping site. If you wait
until you show them a rough cut of the show, some of them might balk
because of how they feel they're being portrayed. It might not have
anything to do with the content or tone, but perhaps as trivial a
concern as someone's Bad Hair Day.
<<And is it true that I can use footage from a location without
permission as long as it's not recognizable?>>
Under American law, you don't need a personal release if a person is
not recognizable. I have no clue about how Britain and Italy view
such things. It's a good idea to have a location release.