Yeah I love all these little questions.
As far as your question about a bridge. I think the wording of her power rule would be "Diana is as strong as any single challenge she faces". That is the game of words that gods like to play. So the bridge would also be considered an adversary simply because she is trying to lift it.
And Diana's aura automatically makes her as strong as the strongest person around her, so even if it's not a villain she would still be as strong as him. And she can use the Lasso of Truth as an extension of that aura, so if she holds onto it and someone else is tied up in it, it counts as her touching them and thus also matching their strength.
And to me the coolest part is that Veronica Cale would punch her and break her hand on Diana's hard skin, and then would get punched back and cry like a baby. But whenever there was a fight versus Darkseid or Mongul or whoever, Diana would instantly be the powerhouse regardless of whatever the writer wants. Like yeah, Thor also has that kind of cosmical rule eith his hammer and there are moments where writers break the rule, but it's very rare and they always have to make up an explicit excuse that points out how much of an exception this is.