Welcome to the Forum TWGirl!
Looks like a nice TW with a few mods. These bikes are easy to work on and everything that the previous owner has done can be reversed if you don't like it.
People extend their swingarms for one of two reasons. One is to allow clearance for a larger rear tire and to improve the offroad capability of their bike. Others do it because they think it looks cool. My guess is that your bike had it done to look cool. The LED taillight and license plate bracket were probably changed because the stock one would have been ripped off by the rear tire after the first big bump with that extended swingarm. Mirrors are mostly up to each person's personal preference and are easily changed. Stock exhausts are often modified to increase performance, but in most cases they just end up making more noise. I felt the same way as you about the look of the rear Cycleracks until I finally got one. They really are great racks and the looks will grow on you with time.
I'd suggest riding it for a while and then make the mods that will make it suit the type of riding that you like to do. There are lots of knowledgeable people on this forum who are happy to help you with whatever you need.