As an overseas American, I'd love some ideas of ways to introduce Thanksgiving foods to friends. The weather is way too hot for traditional casseroles & hot sides/desserts. We need light, summery fare...I had moderate success last year, but failed on several dishes (especially the roast veg. How to do cold, not too sweet sweet potatoes?!). I also have to CONVINCE people that pumpkin is a good dessert food... And possibly doing it for 30-50 people/prepping it in advance because I work 12 hours on Thanksgiving day! Thoughts?

Thanks for the tips & recipes. I'm looking forward to trying this stuff out. Now to get my work schedule sorted so I can get into my kitchen!

As an american who has lived in Australia before... :). First, a lot of our foods are pretty similar. One thing that surprised. Many of my friends was my use of pumpkin in desserts (pumpkin pie, pumpkin bars, etc). Also, American food is very regional, as is Australian.
Re: cornbread, I used the bag of polenta from either Coles or Woolies. Make sure to have honey and butter to go with it... :) i served it with chili and it went over well with both Americans and Aussies. American soft drinks are sometimes available. Dr. pepper, Welch's, or a&w root beer I could sometimes get from one of the Asian supermarkets or somewhere like CandyFix (is that the name?? Hmm...).
Let me know if I can answer any questions. I am sure there are more foods I've introduced to my Aussie friends, I just can't think at the moment :)
Also, don't call it entree, main, dessert. Americans generally go for appetizer, Entree, dessert. Confusing much??

Popcorn balls--add nuts, dried fruits, or chocolate/spices. They make lovely favors-bet they'd be a great dessert as well!

Cupcakes with a glaze instead of frosting (add crushed nuts to the top...I did David Lebovitz' rum cake topped w coconut in cupcake form...um, yes please!). Could also do something like this : http://alisonswonderscraporium.blogspot.com.au/2011/02/i-heart-you-vanilla-cupcakes-with-heart.html.
Or a cake, similarly glazed if you're concerned about frosting, like this if you want something a little "special":
http://www.swiss-miss.com/2011/02/heart-cake-tutorial.html
I have also seen Swiss roll cakes with designs - Could fill any way you like and decorate to follow the wedding theme.
Of course, cookies are probably your easiest answer. There really is nothing wrong with a few lovely types of cookies. You can mix it up by doing some different flavors or matching colors/shapes to the theme. I've done matcha macarons w/ red bean filling & rosemary shortbread with tomato jam centers. Still went down really well :)

On snacks...
Frozen grapes are delicious and easy. Have you tried roasting chickpeas? Even my chickpea-averse brother likes them :). Smoothies are quick and can be healthy (frozen berries are easy to keep on hand, too). Yogurt or cottage cheese can both be healthy--get plain and add your own flavors/toppings. Boiled eggs are another easy, high Protein snack. If you boil off a bunch on the weekend, you can use them as a snack, put them in salads, or make egg salad sandwiches with them. Fruit with cheese sticks or nuts are also quick and easy.
For meals, what did you eat before college? Many recipes can be halved or portioned and frozen. I do this with things like lasagna--cut it and have single serve meals in minutes! Wraps or sandwiches (use whole grain/high fiber) or even lettuce or cabbage wraps for when you're home are filling and quick. If you like things like hummus or red pepper/sun dried tomato dips, those can double as sandwich spreads as well. I love to make stuff that does double-duty. I have made stir fry type stuff for lettuce wraps, then leftover filling can be put with rice for another meal. Sliced vegetables with dips are great for snacks or lunches, then the leftover veggies can be chopped up to be part of a salad later on (or, depending on the veg, possibly into soup). Roasting vegetables is another great, healthy option. Leftovers can go into other dishes--salad toppings, soups, casseroles. I do this a lot. Leftover root vegetables can be amazing on salad, then the next day get puréed into a yummy soup. Add some beans or meat and you're good to go!
Another thing that I'm loving lately is homemade potstickers/Asian dumplings. A few weeks ago, I cooked some chicken and then added things like cabbage, onions, soy & oyster sauce, ginger/garlic/white pepper,sesame oil, and any other vege that seemed appropriate...and chopped it in my food processor. I then took a bunch of wonton wrappers and made dozens of dumplings (watch tv or a movie...) , froze them on trays, then stuck them in ziplocs. When I'm in a hurry, I toss a few in a pan and make a quick Asian-ish salad while they cook (or, if I'm really lazy, just go with the potstickers). They go over really well and have saved me so much time lately! They can be as little time consuming the first time, but once my Taiwanese friends showed me how to fold them up, it really isn't bad at all.
On juicing...sorry. I just don't like it. But my family did it quite a bit when I was a kid. Carrots and apples are popular, as are greens (but you don't get much juice from things like spinach...). Lots of recipes available online. Also, if you juice carrots or apples, make carrot muffins. Zucchini, make zucchini muffins. If you juice spinach or kale...maybe don't make muffins out of those! ;)

One of the hottest items with a youngish crowd we had recently was an afterthought -- rolls (Costco bulk...), a slice of processed cheese, sandwich meat (ham or bologna) and a squirt of dijonnaise. Even with all the fancier foods available, they kept grabbing those sandwiches! Fruit and veg platters also always go over really well, as do some simple cookies like choc chip or snickerdoodles. Kettle corn has also gotten oohs and aahs when young people are over.

When I worked in a developing country in N Africa, there was a popular doughnut-type food the locals called zalabiya. In the mornings on the way to work, you could always find a few ladies with buckets of dough hand dipping balls into the hot oil, frying, and then tossing in sugar. 6 or so of the balls cost about 50 cents, and while they tasted delicious they could also give you a mean stomach ache!