It's certainly important to devote time and money on driving skill, but if you can't make that kind of commitment maybe your money is better spent of physical mods to your car you can touch and use everyday.
As far as suspension goes you can improve handling while sacrificing ride comfort by adding coilovers, sway bars, stiffened mounts, etc. As Dean pointed out you can spend tons of cash on coilovers and you get what you pay for.
In the power department the way I look at I see two different camps,
1) You have a WRX, you want it to go fast. You buy turbo-back exhaust, new turbo, injectors, fuel pump, get it tuned make 250 at the wheels and wait for your transmission to break.
2) Buy an STi.
The above camps are an everlong discussion in the group. Some people have bought and STi(2) and some have replaced or are replacing the transmission in their WRX(2)! Some are on the fence(3).
You say you have some nice tires? What are you running? Many people on the forum have dedicated snow tires.
For the dirt you could go all out:
http://www.fourstarmotorsports.com/C...rstone_106.htm
If you plan on really driving in dirt and snow you might want to consider protective 3M film for the front of your car. Although if you have an 02 it might already be pretty hammered. My 03 is not that great looking and I try to baby it, it’s black.
and done.
maybe some else can fill in my blanks because it's kinda of a lot to consider.