Yes.
I don't know, and don't really care since in the end I am not responsible for the charges. Even my guesses as to how my numbers are being pilfered may well be wrong. It could be a regular vendor that I do automatic recurring charges with that has a bad employee who is pilfering CC numbers, a taxi cab driver, an internet vendor, a bad employee at Chase itself, or someone looking over my shoulder and stealing my number when I am using the card. Either way, when they get the card info, I am sure it is sold to someone else (we all saw the 20/20 episode). Wherever it is happening, I sure I am not the only one it is happening to. Chase's Fraud dept will find them eventually.

To get a more accurate answer, your question would be better asked to Chase or other Credit Cards' fraud departments, but then again they probably would not share that information. At least I wouldn't if I were them.

I originally guessed the internet because that is where I do the vast majority of my shopping and the main difference between my use of the Marriot and UA Visa cards. I do anywhere from 10-20 internet charges a month including recurring automatic payments, charitable donations, household purchases, and recreation purchases (ski passes, tee times, scuba trips, tours, train tickets, etc.). POS charges include groceries, taxis, drug store, and gas for the most part. The likelihood that it is a POS is low since the card is always swiped, except for the taxis where they still use a paper imprint.