As @kezo says, the stalk gear changers are fine. As well as having one on our current car, I had one on a Mercedes E Class company car many years ago and had no issue with that either.
I haven’t driven the Ford Explorer, but with many cars these days you can adjust the various systems to suit your driving style. Lane assist / steering assist systems can be switched off, or you can have a visual warning only or with intervention. Also, with the adaptive cruise control on our car, not only can you adjust the set distance that you remain behind the car ahead, you can also adjust the speed of reaction that the car picks up speed again when the car ahead moves over. I’ve no idea whether or not all of these adjustments can be made on the Explorer or not but, as with all cars, if these things are a concern I’d advise a prolonged test drive where you can find out.
I’d never take the word of a car salesperson about these things as it never ceases to amaze me how poorly informed many of them are about the cars that they sell.