in 2013 they did a "facelift" changed the bumper, headlights, tail lights, rear bumper (I think) made some minor changes to the dash including the gauge cluster to go from 3 pods to one mainly digital unit. beyond that I think they added sync 3 to the mix in the later years, changed color options, minor stuff. i think from 2016 to the end theyre basically unchanged. they roped the focus and the fusion into the death sentence but those cars were still getting updates, fusion had the sport, focus had the rs and the st, the taurus was left behind long before the decision was made to **** all sedans.
as for a performance shop, there is a lot help here to find one, which ones to try, which ones to avoid, maybe even some in your area, I personally dont have much knowledge about shops or tuners for these cars, I was a big SCT fan but these cars take more than the stock tune or "box tune" options you get with your standard tuner. from what I've seen you will need a custom tune and supporting parts to start your horsepower journey, you can make reasonable power with a decent list of parts but I couldnt even begin with the price tag. all depends on how far you want to go and what youre willing to do to get there, the 400AWHP mark always sounded appealing to me but that takes a good bit more than a tune and a CAI to achieve. I'd search the threads and if you come up with nothing helpful for a shop in your area post a new thread to ask around.