Logistically, it's an enormous task to keep over 10,000 people fed and watered, but Microsoft does an absolutely awesome job of it at TechEd.
Breakfast and lunch is provided in the dining area, which is a huge area central to the Orlando convention center. Friendly and professional staff will direct you in the dining area to the food tables where you grab a plate and dish up. At the end of the line you can grab something to drink. Take out containers are also available if you're on the run to a breakfast or lunch session.
Breakfast normally includes danishes, bagels, fresh fruit, cereal and two or three hot dishes like eggs, potatoes and a meat. The cold food stays cold and the hot food stays hot. Servers are regularly changing out trays in prompt fashion. Coffee carafes are usually available on the table at breakfast and lunch. You will find other cold drink stations amongst the tables, as well, offering bottled water, sodas and teas. Grab an extra bottle or can to drink in the sessions.
If you're running late or don't want to take the time for a sit down breakfast you can grab a granola or cereal bar, piece of fruit or danish from any of the many tables throughout the venue. These tables are constantly restocked. Coffee is usually setup throughout the conference center, as well, in the morning. There are usually espresso stands setup in the Microsoft area of the main floor, hosted by one or two Microsoft product groups. These are pretty popular and may have a line so be patient.
Lunch is provided in the same area and usually includes salad and dressing, a hot pasta dish, a hot vegetable or two, two different hot entrees and bread or a roll. This is all handled with even more efficiency than breakfast, due to the even larger number of people being served. You may note how the staff is very friendly and directs you to the most efficient route to your food and table without making you feel like herd animal. They also do a great job of clearing the tables and keeping things tidy.
If you have special dietary needs (low sodium, vegetarian, allergies, etc.) you can specify this at registration. Special menu tables are provided at the breakfast and lunch dining area for this. You must have specified you dietary requirements at registration to be served from this table.
Refrigerated drinks of water, fruit drinks, sodas, etc. are available throughout the venue.
Throughout the day you will see the feed at the snack tables located all over the conference center change. Around lunch time the snacks and potato chips come out, with more granola bars, Power Bars, fruit, etc. Later in the afternoon comes the always popular ice cream. Dove bars, Haagen dazs, frozen fruit bars, etc. are available, but go really fast.
In short, you'll nearly always find something to eat and drink and it won't cost you a dime.