Once you know your budget(are you doing the work yourself?)I would search online for kits/parts that fit and the pros and cons to get a feel for it and then come back here with specific questions, there are a lot of great article out there on this very topic. Bumpsteer,CC Plates, coil over etc etc., a lot to learn but I love the learning part too. Many times your search will lead back to a Mustang Forum(even this one) etc that will widen your knowledge even better than just asking on a single forum. Not saying this is the case here,but many unanswered/little response threads are because the the other members expect you take a little initiative and check things out first. I have been told many times to try Google, and in not such a nice way on some other forums I have been on.
Yes a lower ride height would help handling and looks, but there are possible downsides.