At age 22, I had never had a cavity, all my teeth were perfectly straight, even my top wisdom teeth. The bottom two were impacted, the left one had only come out halfway and the right never erupted at all. That left one had the gums flapping around and ended up causing an infection, not of the tooth, but the gums. I ended up having that one removed. After the dentist took it out, all my bottom teeth shifted making room for the right one to erupt, again only halfway. I decided to see the dentist about having the right one removed before I got another infection (because that was absolutely no fun). When the xrays were done you could see where all my teeth were still perfectly straight, except the top left wisdom tooth was starting to come down a lot further than the rest, because there was no longer a bottom wisdom tooth to support it. So, five years after pulling the first one, I had the other 3 removed, initially with only the intention of having the impacted one removed, even though the top two were perfectly healthy and had no problems. I had a dentist that wasn't so quick to pull wisdom teeth, even though it is the standard guideline these days, and he even suggested it.
My only advice is that if the tooth that needs to be pulled is on the bottom, you might as well have them all pulled, because it will throw your whole mouth out of balance. Removing a top wisdom tooth isn't going to cause your bottom ones to start coming up, but the rest of your top teeth will likely shift (spread out).
As for any pain, it wasn't anything a couple of ibuprofen couldn't handle. I was totally knocked out having the 3 wisdom teeth removed and I could have gone back to work the next day if I wanted. I felt just fine (though I did take the next day off just for the sake of having the day off, was a great excuse lol I went to the park with the kids).