Should one drink water in only three sips, or does this apply to every drink, such as juice, which is difficult to drink in three sips, and in this case, should one drink it an odd number of times, in five or seven sips?

The Sunnah is to drink in three gulps outside the vessel. This applies not only to water but to all drinks, because the hadiths use the terms "vessel" and "drink," which are general terms. This method is more satisfying, healthier, and more wholesome. One is prohibited from breathing into the vessel or blowing into it. This ruling is a matter of recommendation, not obligation.