There have been 0 cases of EVALI linked to any legally purchased nicotine vaping product. The CDC and FDA have narrowed their focus to E Acetate, an additive to Illegal THC vaping. E Acetate is used to make the THC vapable and appear higher quality than it really is. The E Acetate does not break down in the lungs and causes severe respiratory problems and in some cases death.
No. While it is not 100% safe it is a far better alternative to smoking. The Royal College of Physicians in the UK did a comprehensive study and found vaping nicotine to be 5% of the risk of smoking cigarettes. The UK is starting to do a huge push to get smokers to switch to nicotine vaping. So much so that they are putting vaping retail locations inside hospitals.
No Vapers have been diagnosed with popcorn lung. Neither have any cigarette smokers (but with all the lung illness from cigarettes it's possible to have missed it) and they ingest anywhere from 100 to 750 times more of the chemical than vapers do. Diacetyl (the chemical associated with popcorn lung) adds a butter flavor to eliquid. Most eliquid companies have taken Diacetyl out of their ejuice but there are still some that have trace amounts.