The molecules that carry nicotine in vapor and that in tobacco smoke are a different size, and are absorbed in different parts of the body. Most of the nicotine in vapor is absorbed in the mucous membranes of the mouth, throat, and nose. Therefore, it's not necessary to get the majority of the nicotine by inhaling into the lungs.
I feel its important to exhale some of the vapor through the nose, whether one inhales into the lungs or not. Our taste buds have been damaged from years of smoking. And our sense of smell assists our sense of taste.
This can be understood when you recall having trouble tasting your food when you have a bad head cold. Normally molecules are present in the air which our nose picks up on that come from most foods, but when it is blocked off, the nose has no information to send to the brain. However, if our nose is able to assist our tongues, much of what we interpret as flavor has been contributed by information gathered by our sense of smell.
In short, exhale some of your vapor through your nose. Some of that tasteless flavor from your e-cig may just surprise you.
I don't believe you can overdose on nicotine from normal inhaling or oral absorbtion of vapor. One would get plenty sick before that could happen. Headache, nausea, lightheadedness, jitteriness. Similar symptoms to another commonly used stimulent - caffeine.
Any
eliquid containing nicotine should be wiped off skin surfaces within a few minutes of contact. Common sense would dictate not to consume orally. Keep nicotine liquids in child proof bottles or way out of their reach.