Welcome to the club!
There is definitely quite a difference between the WRX and a Mustang. I would recommend you try driving one before you get too far along. Once used to a WRX, a RWD V8 seems to fail miserably for anything that is not straight line and clean/dry pavement. However, coming from RWD V8 the WRX will tend to feel irritatingly wimpy on low end torque (especially when not launched).
Where abouts in VA are you?