1 & 2: Fraction: Chances for/Total Chances Odds: Chances for : Chances against. I am not debating what you have personally heard of
more. In my experience people use odds ratio a *lot* and a lot of people find probability and math very intimidating.
That does not necessarily mean they use the right concept mathematically, i have seen many use chances as chances for/total chances, without knowing they are technically using a probability ratio, but that is ok in my opinion atleast.
3 Am 95% confident that chances of smokers getting cancer are between 1.82 to 2.10 times higher than a non smoker.
95% is just a commonly used percentage in this context, like 20% sampling for sql server statistics.
"95% of the time, when we calculate a confidence interval in this way, the true mean will be between the two values. 5% of the time, it will not. Because the true mean (population mean) is an unknown value, we don’t know if we are in the 5% or the 95%. BUT 95% is pretty good so we say something like
“We are 95% confident that the mean time it takes all workers in this city to get to work is between 18.3 and 23.7 minutes.” This is a common shorthand for the idea that the calculations “work” 95% of the time."