Eating out and Food

Eating Out

Restaurants are cheap, and eating out is very common. (Of course, expensive restaurants are expensive, but they are less expensive than the UK. Cheap restaurants are cheap). Things to note:
Food is (or can be) cheap. Drinks aren't. You can add a surprising amount to your bill by having a few drinks.
Tip. You have to tip. You will be frowned upon by all and sundry if you don't. At least 15% of the bill, or more if the service was good - tipping 15% is the same as tipping nothing in the UK. (It's sometimes a bit tricky to know who to tip - it's OK, this confuses Americans too, so ask around). (There was a recent case of a group who refused to tip, on the grounds that the service was so poor - the restaurant called the police. The police came. The police arrested the non-tippers. They weren't charged in the end.)
Sandwiches

If you buy a sandwich from a delicatessen, you'll be asked what sort of bread you want. They won't tell you what the options are, and it's sometimes hard to see where they're written down. The usual choices are white, wheat (which means wholewheat), sourdough and rye. You'll also be offered cheese - every sandwich comes with cheese. The standard options are American (bland), pepperjack (bland American cheese, with chilis in), cheddar (slightly less bland, and orange) and swiss (slightly less bland, with holes in). If you just want a cheese sandwich, they might act as if you are missing something. Cheese in a sandwich will always be sliced.
Restaurants (and I guess people at home) don't put butter in sandwiches. They have mayonnaise (which, naturally they call mayo) and/or mustard. When you buy a sandwich you'll be asked which you want - don't say neither, assuming that there will also be butter (or margarine), 'cos there won't be and it will be a little dry.

Drinks

Lots of smaller cheaper restaurants - pizza joints, and the like, will have only fountain drinks - there won't be any fruit juices. The only diet drink that's usually found is Diet Coke.
Eggs
If you order fried egg(s), you'll be asked how they should be done. Sunny side up means that they are not flipped, over-easy means flipped briefly, over medium means flipped for a longer time. (I'm not sure what comes after over easy).
Pizza
Pizza is very variable. People from New York, or the east coast generally, get very upset about pizza on the west coast, because it isn't as good. But on the west coast the Sushi is better. The default pizza is pepperoni. If a place sells only one kind of pizza, it will almost certainly be pepperoni.
Avocado
You get avocados all over the place. It's an option in Subway for your sandwich, it's an option for your burger in bars, and it's often an option in your omelet. It's also frequently available as a side dish. I like avocado, so this is good.

Some Strange Foods

It might be me, but here are some things I'd never heard of before I came here:
Lox: Los is very thin sliced cured (not strictly smoked) salmon. It's also a good word to play in scrabble.
Arugula: It's rocket.
Jicama (pron hicama): A mexican vegetable, fairly tasteless, the consistency of a turnip, and the taste of tasteless lettuce. It sounds unpleasant from that description, but it's not, it's crisp and crunchy, and interesting enough if you dip it in something.

Tamale: Like a Mexican pasty, cheese or vegetables or meat, wrapped in ground corn, then wrapped in a corn leaf and steamed.
Quesadilla: A Mexican grilled cheese sandwich, a tortilla (flat bread) filled with cheese, and other stuff, and grilled.
Jack: If you see jack on a menu, it's cheese (bland, American cheese).
Don't forget that chips are fries, and crisps are chips.

Food and Cooking

Grills
What we call a grill, an american will call a broiler, and will not use very often (as far as I can tell - when I arrived, I asked a colleague what a broiler was, because our stove had a switch on it that said broiler - he didn't know). A grill cooks from underneath, and can be a griddle - like a very large frying pan, or can be like a barbecue - a barbecue is a grill, but you can also get electric grills for your house. When something is advertised as grilled, that means it's fried, although usually with little fat.
One American standard is the grilled cheese sandwich - this is a cheese sandwich that is fried (with some oil, but not as much as, say, fried bread). For many Americans grilled cheese sandwiches have a special emotional resonance, it was what their mother made as comfort food.
Stoves
The cooker is a stove. They are basically the same as ours, but often wider, and sometimes have a griddle in the middle. I've never seen one with an eye level grill (broiler).
Bread

Bread is relatively expensive, and to the British palette often unpleasantly sweet. Look out for those that say 'sweetened with honey' or 'sweetened with molasses' or anything similar, and avoid them. Supermarkets don't tend to bake their own bread, so it's never super-fresh and delicious. In Los Angeles at least, many of the supermarkets get their fresh bread from the same place (the La Brea Bakery) so you don't get posher bread by going to a posher shop, you just pay more. People from the east coast say that the bread is better there.

Baked Potatoes
Almost never seen them. There's a store called Spudnuts. You'd think that would sell baked potatoes, but it doesn't, it sells doughnuts. (Or donuts, if you want me to hate you forever.)

Sugar
Americans like sugar.  It's hard to find diet soda when you're out, apart from Diet Coke, I've never seen Diet Sprite, or anything like that, in a restaurant or cafe.  Canned fruit is almost always in sugar, rarely in juice - and when it is in juice it's 'lightly sweetened' juice.  I bought some frozen raspberries from a supermarket the other day, which had added sugar.