A lot of American-Chinese food is fried, and actually unhealthy. A good gauge of how good Chinese food is: are there any Chinese people in there eating it? I've only been to one restaurant where there were some (a lot, actually), and it was in Chinatown in Washington DC. And it was the best Chinese food I have ever had. The meat was light and would just melt on your tongue. Probably because it hadn't been fried in who knows what and left under a heat lamp.
Lettuce is dicey. I, and a few others, can tolerate it if it's cut up fresh at home (pre-cut, bagged salads are evil, as are most salad bar salads), but a lot of people can't tolerate it. You'll just have to try that one out for yourself to see which camp you belong to.
After recently returning from Britain, all I can say is that American restaurant food is AWFUL! If you could have a British tomato or green pea or fresh bit of fish, you'd know exactly what I mean. Although I can't bang the seafood in Charleston; we ate some mighty fine seafood while there. But most everywhere else in the US uses nothing fresh (at least not in the Southern states).
I think your best bet for eating out is to avoid chain restaurants like the plague and go to family-owned places that are a bit more upscale (no meat-and-three homecooking places; they have lots of fat and grease). In my town there's a lovely italian place and a sort of steak place which makes a nice chicken/cheese/bacon thing and has WONDERFUL chicken and rice soup. Again, their chicken just melts in the mouth, so that's how you know it's light and easy on the stomach.
The other thing I learned while in Britain is that a normal portion of food is an appetizer portion in America. If you get dragged along to a chain restaurant, just order an appetizer, if there's one on there that's not fried. At the very least, you will have a smaller portion of it to eat, so it will make you less sick in contrast. It's a proven fact that if food is in front of you, you will eat it. And as most of us pay for what we eat later, not immediately, it's very easy to eat a lot of something that's not going to like us later. I have also found that some things I can actually tolerate in small amounts; it's the overindulgence that gets me. So there's another place were appetizer portions may help. Most places with a buffett (Chinese places) also have a menu; you're always better off ordering a single plate of food from the menu than helping yourself to whatever tempts you at the buffett table.
As for fast food, I almost never eat it any more. Panera Bread seems to be a pretty good place to eat; other people on here have said they can tolerate their sandwiches. I love their chicken frontega. They're built into malls a lot of the time, so it may be hard to find one as a drive-through place. Chick-Fil-A is another place that I have found very tolerable. They use peanut oil to fry their chicken in, and this doesn't bother me at all, compared to partically-hydrogenated whatever, which can really mess me up. Peanut oil is one of those healthy fats, so I think that's what makes the difference; I can tolerate healthy fats, but not the trans fats or much saturated fat. So I can actually eat Chick-Fil-A's fried fare, although their chicken soup is the BEST! They also have good chicken wraps (KFC does too, actually), so that's always a good alternative. The burger places are mostly out, although a burger is always better than a fried chicken something-another. I do alright with Krystals (Southern version of White Castle), but I never eat more than 3-4 with a small fry. People who consume them by the dozen call them "gut bombs". Before or after my stomach problems, I have never had a krystal bomb my stomach; again, it's all about small portions of iffy things.
Oh, and stay away from tea and cokes to drink; caffeine messes my stomach up terribly and isn't very good on a lot of people's on here either. Coffee is obviously another one to avoid, although you have to give up the de-caf as well, as all coffee, regardless, has caffeine in it, and it's acidic and not good on your stomach for that reason too.
I eat a light breakfast of either yogurt, oatmeal, bread and jam, or a milk-based supplement drink. But I will recommend turkey bacon. It may take a little getting used to, because it doesn't taste like pork bacon, but my mother converted me and I converted my husband. Cook it in the microwave on top of a paper towel and be amazed at the lack of grease and the crispiness; best of all, there's not fat rind to have to pull off. Regular bacon gives me heartburn, but I can go through the turkey bacon like it was nothing. I can also actually tolerate mild sausage, although, for some reason, eggs have gotten to where they don't like me much at all anymore. Omlettes are the absolute worse, regardless of the ingredients in them. I don't know what it is about making an egg into an omlette that makes me have D, but I can tolerate scrambled eggs much better.