In recent years, though has taken on a new kind of slang meaning, used mainly by young people. It's hard to explain but it's used almost for emphasis. For example if someone posts a photo meant to call attention to a certain feature, someone might comment "Those eyes though" or if someone likes your new jacket, they might say "That jacket though" It also just gets thrown on to the end of sentences for no apparent reason which is the case in 2-5.

I would say that they all imply a contrast. In 2-5, you don't have the whole conversation, but they imply a contrast to what another speaker has already said. Even in your original question, you have implied a contrast with what you previously said!

Though in number 2 - 5 means despite the fact, also. 1 though means however.