Early Rails Camps had group efforts providing food for everyone, but as the events grew, these efforts did not scale - especially when it's the attendees who were doing the food preparation. So, caterers are engaged for camps to cover the food required for the event.
Unless you're making special plans for a meal or two, this will include dinner on Friday, breakfast, lunch and dinner for Saturday and Sunday, and breakfast on Monday (8 meals in total). Some camps have also supplied morning and/or afternoon tea, which is appreciated as well.
Often venues will insist on using their own catering service - though if you're allowed to bring in your own caterers, it's worth getting a few quotes to ensure you're getting a good deal for good food.
Ideally, you want to be working with the caterers to approve/adjust their suggested menus. It's best to make this clear with whoever you engage to be caterers.
School camp caterers are used to preparing meals for children who are active all day, which is different to a group of mostly sedentary adults. So, you should make it clear to the caterers that you will require a menu that has lots of fresh vegetables and is not carbohydrate-heavy.
An approach that has worked in the past is having each component of meals separate, so people can choose just the options that suit them (which makes life easier for people with allergies, intolerances, and strong preferences).
Having food available between meals is important - sometimes people miss meals, or need some extra things to snack upon to keep them going. Fresh fruit is a great option for this (healthy and cheap).
It can also be helpful to have a late-night supper available to help soak up the alcohol that people are drinking. Party pies, pizza slices and other savoury snacks have been welcome dishes for this at previous camps.
The usual approach for drinks is to provide a variety of beers, ciders, teas, juices and soft drinks for attendees. Certainly, having many options of each of these is recommended, but it's best to encourage attendees to bring their own hard liquor if they're so inclined.
A dry (alcohol-free) camp has not yet been run. That doesn't mean it shouldn't, but if you make this decision, you should make it very clear on the website and other event notices. Discussing this with past organisers is wise.
Or, you could let everyone bring their own alcohol, and not supply any. Again, this would be something to make extra clear in communications, and it'd be wise to add a battleship stop for the bus journey to the venue.
Some camps in the past have used kegs for beer and cider. This has proved to be problematic: you become reliant on equipment you and other attendees might not be familiar with, those who do get trained on the equipment must always be present (and reasonably sober), and it might be harder to offload any unused kegs.
Approaches to coffee have varied. The extremely hardcore will bring their own gear, but usually at least an espresso machine is provided. Sometimes a barista is hired to be on-site for Saturday and Sunday (within given hours, or staying on-site if they're particularly keen).
If you're planning on bringing a lot of food and/or drink to the event (e.g. snacks and drinks), it's worthwhile checking whether supermarket delivery services (Coles, Woolworths, etc) cover the area. This can potentially save you a lot of transport hassle (though you'll need to manage leftover supplies yourself).