So you're willing to sell off your privacy for a few bucks?
Not under those terms, which is why I don't use store-specific cards (since it's already bad enough that credit processors want to track me). If there were a pay service that could replace FB in all aspects, minus ads and data-gathering, I'd be more than interested to look at it.
How does it feel knowing that there are complete strangers out there that think they know you because of the data they collect on you about purchasing habits?
Honestly? It doesn't bother me. Similar to "How does it feel [...] that think they know you because of your pseudonynmous posts on Slashdot?" I don't do anything important on Facebook, similar to how I don't do anything important on Slashdot. Sometimes, I make posts that don't reflect my feelings, just for a change in pace. Facebook wants to see my false information? Meh.
How will you feel about it when someone gets it wrong?
Amused, so far. FB has been trying to guess where I live for years. I don't think that it's ever guessed the right city, and it guesses the right county only occasionally. More commonly, it picks a state across the country where it knows I have a lot of friends, or in another country. I commonly look up products that friends are interested in, but that I don't care about. I mark random ads as offensive. If they can actually filter the signal from the noise, I actually think that's pretty cool, and I hope some papers eventually get written and released, based on the methods. They've done the work, and all based on information that I wouldn't have a problem yelling to random people on a street corner.