Hotpot is arguably the easiest meal to cook and a great way to entertain a large group of people. There is some thought/organisation involved when it comes to large groups but compared to other types of meals, I'd say that having hotpot comes in at the cheapest and you have everyone generally quite full afterwards. Here's what I think are the hotpot essentials (for large groups).
A place that's free with a dining table, hotpot stove, pot and nets (It's preferable to have two or more pots going if you have a particularly large group). Chairs aren't completely necessary as you'll be standing around the hotpot for most of the night to get to the food.
For large groups, I'd advise against getting the entire group to go shopping - it just doesn't happen. Nominate two (preferably one girl/one boy, preferably with some experience at the shops) to go shopping. Girls generally have a better idea of what's required to cater for the whole group, the boy generally makes comments re. the volume of food required (plus they can hold the shopping basket as it starts to get heavy). You'll find you can get most of what you'll need at Asian grocery stores (ingredients, gas, stove, utensils etc.)
The people: Make sure everyone turns up with a stomach to eat and about $5-15 to split the shopping bill. To date, I haven't had to pay much more than this.
Assorted soup bases: You'll find that about half the group are adventurous and can take the chilli but for the other half, a seafood soup base or chicken broth will come in handy. Alternatively, you can skip the soup base and start with water. Over the course of the meal, the flavour of the food will boil into a soup.
The ingredients: Assorted Meats (Beef, Lamb, Chicken - generally the fattier the meat, the tastier it is), Chinese Cabbage, Raddish, Fish balls, Cuttlefish balls, Beef balls, Fish tofu pieces, Fresh tofu, Enoki Mushrooms, Beef Brisket, Assorted dumplings, Udon noodles, Fresh Egg, Soy Sauce, Sesame Oil, Jimmy's satay sauce. There's all sorts of ingredients you can buy but the above are pretty much your staples. Oh, and don't forget drinks - you'll probably get thirsty! You'll find the more people you have for dinner, the more budget you have to buy a range of ingredients. Might I add, make sure you keep hot water boiling in the kettle as you'll need the hot water to top up the pots as they start to boil down and evaporate.
The cleaning: Don't forget that there is a bit of cleaning to do afterwards. A handful of helpful hands will get the job done in no time. Probably the most annoying thing is cleaning the hotpot nets which get egg and bits of meat caught in the cracks. Whilst having hotpot, be mindful about the food you put in - always make sure that no food sinks to the bottom and gets forgotten as you'll have some trouble getting that off once it starts to settle at the base.
Fruit to finish - It's almost the Asian way to finish off any meal.
Notice how the oranges have been cut! I thought I'd have a go and do what they do at Chinese restaurants. It actually wasn't too hard although less juicy oranges will make less of a mess - I had orange juice running everywhere on the chopping board. Could be that I wasn't doing it right but the presentation of the oranges did get them going like hotcakes and that's surprising when you have a group where the majority of them are boys!