3.) Hiccups - Also caused by a lack of air exchange in live-lung capillary vessels. The hiccup action aids in the unclogging of small blocked passages which have constricted and filled with thick mucus. (After heavy smoking, and while stressed, these symptoms can occur without stomach air/gas being present.)
It goes away by taking a few deep breaths, and one deep breath prior to inhaling a restricting gas like carbon-monoxide or carbon-dioxide saturated vapor. (It is the opposite reaction of hyperventilating, but similar a situation.)
Yes, Acne is a common issue with quitting smoking. This is also related to stress-levels as well as toxin levels in glands being excreted.
Multiple, small, mouth-only puffs, like smoking a cigar, can help reduce some of the associated cross-over symptoms.
Remember, cigarettes are also filled with other speed-like stimulants. Nicotine is only the chemical that is responsible for the craving, not the, "high". Cigarettes are also filled with urea for flavor and formaldehyde for smoothness. This along with many of the hunger-suppression chemicals, which mess with your digestive track, are no longer present in an e-cig. (Essentially, many of these symptoms are your body reacting to the damage it now feels, which was caused before, and suppressed by the anaesthetic reaction from normal cigarette chemicals.)
You get a similar reaction if you eat McDonalds every day, and suddenly stop... or never eat there, and then start eating there. Your body makes a temporary adaption to the new foreign chemicals, or begins to show signs from protecting your body from elements that no longer exist within your body.