you're on the right track here... the best bang for the buck is upgrading to ss lines, upgrading fluid, and upgrading pads. if your stock rotors still work then they are fine and unless you're tracking the car regularly then the stock calipers can hang in there fine too.
most go with goodridge ss lines... but i would assume that most are pretty equal.
most go with ATE Super Blue or ATE TYPE 200 brake fluid... they're actually the same thing, just differenc colors for ease of bleeding. Its a good brake fluid but doesnt break down nearly as fast as other high performance fluids so its a good choice for a street / light track car.
now for pads... thats the question. more aggressive isnt necessarily better. i'd recommend a street pad or a mild track pad at most, depending on the driving you do.
different pads have different operating temp ranges, and no matter how hardcore you think you are, its just not physically possible to heat up your brakes enough on most public roads as it is on the track. what this means is if you get track pads and use them on the street they will never heat up to proper temp and as a result offer poor braking.
as far as street / autox / light track pads go, i would recommend:
Street / Auto-X:
Ferodo DS2500
Carbotech Bobcat
Hawk HPS
Light Track:
Ferodo DS3000
Carbotech Panther Plus
Hawk HP+
These are the pads I either know about or have experience with. Of course there are others out there that might be great (like i hear great things about Pagid pads, but dont know much about them).
hope that helps!
edit: another upgrade i've been looking into is a Brake Master Cylinder Brace... i know that Perrin and MRT both make them, they arent too expensive, and I've read some promising reviews...
edit2: I forgot to mention a great upgrade for RS and WRX guys... you can do an "H6 Upgrade" as it is called... it uses a Legacy H6 rear rotor and caliper bracket. The rotor is 290mm instead of the stock 266mm... and the bracket relocates your stock caliper out farther to work with the larger rotor. This increases rear clamping force and shifts the brake bias roughly 10% rearward on a very front brake biased car, so it is a good thing.