Bread may be made from wheat or rice or garbanzo bean flour (or other flours)
India is a land of many people with many different food traditions and restrictions. Everyone in the restaurant business pushing Indo-Pak food is usually knowledgeable in those restrictions and will know precisely what a particular dish is made with. Feel free to ask ~ I've been in top end Indian restaurants and dumps and they've never failed to be polite when it comes to telling me what's in a dish.
Chicken dishes are usually going to be served in a spicy sauce, although chicken masala is usually available stand alone. Use the green sauce as a dip for your bread ~ be careful because some people toke that stuff up like you wouldn't believe. Learn about scovil units too.
Rice will usually be a bismati, or jasmine. This is indicum rice and if you prefer japonica THEY DON"T HAVE IT ~ but they may be serving an American long grain indicum without the funny flavor. Pour on more sauce ~ in a buffet there are probably going to be 5 or 6 sauces. Otherwise you can order 8 to 12 different sauces that'll come in several small bowls.
Make sure your water is served first.
My favorite places serve everything on paper plates so they can be tossed away and no one has to violate anyone's food restrictions ~ in India they tell me the serving would be on a banana leaf. The trick with these places is they simply make more sauces and chutneys than you find in the more Westernized restaurants.
We do this several times a year.
Oh, best bet for newbies at an Indian buffet is a dish made with what seems to be cauliflower with potatoes, covered in a thick cheese and/or cream sauce ~ and moderately spiced. This is mom's home cooking in that part of the world. Sometimes there'll be some peas in the mix ~ and frequently carrots ~ they aren't as foreign as you thought
Mark