One of the reasons that coffee or other caffienated drinks are limited on SB is due to, in some people, caffiene can cause an insulin spike in your system, leading to cravings. Some folks can handle the caffiene, some can't.
Water is NOT the only thing you drink on this way of eating. Water is considered an important part of any diet, and SB is no different. Many times when the body signals that it may be hungry, it is actually thirsty, and water, if for no other reason, will help to fill the percieved void.
As for other beverages - avoid high concentrations of carbohydrates in your beverages. Diet sodas are fine (for some, it is better to use caffiene free). Decaf coffee or tea if you are susceptible to caffiene induced cravings. Stay away from fruit juice - you are better off eating the entire fruit - not only will you get the juice, but some fiber to go along with it.
As for being good for people on the go - that depends on your definition of "on the go". I will tell you this - I started this with my wife on 5 January. To date I have dropped 27 pounds - I am never hungry, no cravings for the foods on the "Foods to avoid" list, and my energy levels have skyrocketed. I am sleeping better, my clothes fit better and my overall outlook on life has improved. And, there is a LOT of support here as well.
As for the meals and snacks - this diet does not tether you to a menu. If you don't like the recipes in the book, substitution is easy, no matter which phase of the diet you are on. You don't measure anything, you don't count anything - you change the chemistry of your system by avoiding the bad carbs and fats that so many people fill up on and replace them with carbs and fats that are good for you. You become very in tune with the way your body processes certain types of foods. The diet gives you an easy way to substitute foods you like by providing a "Foods to Enjoy" and a "Foods to Avoid" list.
The snacks are important in that one of the major goals of South Beach is to stablize your blood sugar all day long. Skipping snacks may cause an marked decrease in blood sugar, causing you to over react and eat the next thing that appears in front of you.
Give it a try - there are a lot of folks here doing South Beach and we are losing a PILE of weight and getting healthy at the same time.
Hope this helps,