Holy moly Brandon, I love your tenacity! First Mustang at 14!!! You are a real credit to the young generation...took me 22 years longer than you to get my first Mustang (although I have owned over 12 other cars, houses, boats, married, and had three kids during that time).
I want to be a wise guy and tell you to wait at least until you can drive before you start dumping money into that thing...but, heck, why not? You can still enjoy riding in the darn thing and hopefully you have an older family member who can teach you to drive the thing safely in an open parking lot (my wife started to drive when she was your age...she lived on a farm). I can see that you already have respect for cars...or you would not have bought it.
Hey all you junkie Rice Burners.....look out for this guy.
My only advice would be to not let the car interfere with your education...I mean the kind where you get a diploma and a degree. That is what is really important. Be safe too...a Mustang is like a loaded weapon...it's a big responsibility.
On to wheels. It's a personal choice really. Wheels can change the appearance of a car more than anything but a paint job. There are lots of choices out there.
Check out ebay and watch for auctions posted by AFS Wheels. You can win a set of four Cobra R wheels for less than $400...chromed. They also have lots of other choices. You should be able to get a nice set for under $600...believe me. Don't spend too much, you may need it for engine work...it is an older car and it makes no sense to spend 50% of the value of the car on wheels.
Also, look at
www.wheelreplicas.com. They have some real nice "knock-offs" and low prices. Great sales too if you catch them.
I graduated from college in 1990, so I remeber that car well. The LX was notorious for whipping the GT. Some of the LX's could be had stripped...no AC...no nothing. These were the real screamers when new.
Good Luck!