It would help to say that it's from Friends. It's very particularly American humour, reflecting their culture, so it doesn't always make sense to others like me. 1: I guess it may be referring to nuts being a slang term for testicles. 2: No idea. Maybe it's a joke about boys wanting to play with dolls houses. 3: River boats are not so much for transport, so much as entertainment. The comments are all suggesting he looks like an entertainer, and/or very old-fashioned. They may even be referencing old 'Black and White Minstrels' shows. Cotton gins were invented in the South over 200 years ago. They are saying his style is a similar age, and fitting to that southern culture as well. I'm not sure how to explain 'make a point'. We use it in several contexts. It can mean 'to be deliberate, or do something deliberately'. In this case, another way of saying it is 'make a statement'. It means that he has done something to say something non-verbally. In this case, I think it is that he is establishing his independence, and also perhaps that he has a quirky dress sense.

3. Ross: (entering, wearing a white suit with a little red bow tie) Hey, you guys! Guess what? Rachel: (looking at the outfit) Got a job on a 【river boat】? Ross: Y'know what I didn't wear this suit for a year because you hated it. Well, guess what? You're not my girlfriend anymore so... Rachel: Oh I see, so this suit is【making a point】. Now that you're on you're own, you're free to look as stupid as you like. Ross: (to Monica) You like it right? Monica: Oh absolutely. I like it even more on you than I did on Colonel Sanders. (Ross starts to leave) Ross! Ross! I'm kidding! Rachel: Yeah, come here! Monica: What-what was it you were gonna tell us? Rachel: Yeah. Oh! Was how you invented the 【cotton gin】?! Q3. I understand that KFC founder wears a suit like that. But what does it have to do with “river boat” and “cottin gin”? Also, a language question, what does rachel mean by “make a point” here?