In Holland eating out is basically the same as anywhere else. You sit down, order food, eat, pay, leave. There are some things you should know, though.
First of all there are two ways of eating out (as in most Western countries): fast food and restaurant.
Holland has a couple of the (in?)famous American fast food chains; McDonalds, Burger King, Kentucky Fried Chicken, etc. McDonalds is the most common, found in any city with more than approx. 50 thousand inhabitants. You'll also find McDrives along most major highways.
In addition to this ready-made fast food, Holland also has loads of 'Snack Bars'. You'll find these in every town in Holland, and they serve fried foods like French Fries ("Patat", which in The Netherlands is usually eaten with mayonnaise), hamburgers, etc. There are also some typically Dutch snacks available there, like the "kroket" (meat ragout in crunchy coating), the "Frikandel" (just fried meat), the "Nasibal" (fried spiced rice in crunchy caoting) and the "Bamischijf" (crunchy disc filled with noodles).
Do realise that almost everything in the Snack Bar is fried or deep fried. Not a place to go if you're on a diet, although most Snack Bars also do sandwiches, ice cream and drinks.
'Regular' restaurants are basically the same as anywhere else. Especially in the four major cities (Amsterdam, Rotterdam, The Hague and Utrecht) you'll find almost any quisine available in any price range, from French to Korean and from Argentinian steakhouses to vegan/biological eateries. Most smaller cities have enough of a choice in restaurants and bistros in the regular cuisines (French, Italian, Chinese/Indonesian, etc.) for you to find what you like.
If you're looking for traditional Dutch food you're probably going to have to spend some time to find it. Dutch food is traditionally a 'one-pan' dish, based on a local vegetable and potatoes plus some meat (a throwback to the agricultural history). If you would like to try it, look around in one of the four major cities, especially in wintertime. TIP: In winter a lot of local bistros sell the traditional 'Erwtensoep', a thick, heavy pea soup with smoked sausage and bacon. Very nice...
2.2.: EATING IN AND SHOPPINIG FOR FOOD
If you want to eat in, there's plenty available in the super markets. All supermarkets have whatever you need for a basic meal and the larger ones also have some specialties. Almost all supermarkets also have a fresh produce section, so shopping for food should not be a problem. If you want some really fresh vegetables, fruit or meat, visit a "Markt" (open-air market). Most towns have either a full-time markt in place, or have one on a fixed day every week. There you'll find a lot of fresh stuff, usually cheaper than in the stores.
Some of the major chains of supermarkets in Holland are: Albert Heijn, C1000, Edah, A&P, Spar, Super and Konmar. Service there is usually very good if you need anything you can't find.
When shopping, also look out for the smaller shops, they usually specialise in a certain area of cuisine or food, and the quality is generally excellent.
Holland is pretty liberal with regard to alcohol, but alcohol will usually not be sold to obviously intoxicated people, people under the age of 16 (beer and wine) or under the age of 18 (distilled liquors).
The Dutch mostly drink beer or wine, although the stronger stuff is quite popular too. One specifically Dutch drink is "Jenever", a strong distilled sort of gin, made from juniper berries. It's served chilled in a very small glass and really warms you up on a cold day...
A small note: if you decide to get drunk in public that's up to you, although it is not really accepted if you've very drunk and obnoxious. Bar personnel will not serve someone who is obviously drunk, and if you're outside creating a ruckus there's a good chance the local police will pick you up and detain you for a night (to sleep it off usually).