Upgrades...
Performance brake pads will decrease your stopping distance, and have an increased resistance to fade. Also, when buying brake pads, you need to be realistic in their use, and buy accordingly. For example, if your car is going to be a daily driver, you don't want to buy a race compound pad, because their operating temperatures are different. A race pad needs to be warmed up to work properly. You can actually see decreased performance on the street with race pads, when compared to stock. Also keep in mind that performance pads will tend to wear out your rotors faster, and may not last as long as stock pads. They also tend to make more noise.
Brake fluid won't become an issue for a street driven car, but if you plan on going to the track (road course not drag strip), and you put in more than a few minutes of aggressive driving, you will eventually boil cheap, or lesser fluids. In my opinion, if you are going to have your brakes apart for a system rebuild, why not spend the extra money and get some good fluid in there. That way, if you do decide to run a track day in the future, you will be good to go. There are a lot of different performance fluids out there... ATE Super Blue, Motul 600, and Castrol SRF are all good fluids, but expect to pay a little more than the stuff you can get at AutoZone.
Stainless steel lines are probably one of the most important things on the list of things to do. There are several guys on this forum who have had brake line failure from old crusty rubber lines. Talk about a scary experience. The stainless lines also have a lot less flex, and will increase pedal feel.
Slotted, drilled, or dimpled rotors are all good ways to try and keep brake temps down. The idea is that when your brake pad is being pressed against the rotor, the heat caused by friction creates gas, and this gas can become trapped between the rotor and the pads, causing the pads to "float" away from the rotor, which reduces the clamping force. A slotted, or drilled rotor gives the hot gas somewhere to vent. The texture of these rotors also help de-glaze the pads keeping them constantly fresh. The downside of this is decreased pad life. As far as the difference between the 3 styles of performance rotors... slotted rotors do a good job of venting, but the slots don't penetrate to the center of the rotor which is vented itself for cooling. Cross-drilled rotors have holes that go all the way through the rotor into the center of the vented rotor. This may allow for increased cooling, but drilled rotors ALWAYS crack eventually. Even our Porsche street cars with factory drilled rotors will eventually get tiny hairline cracks around the holes. Drilled rotors need to be inspected FREQUENTLY and replace when any signs or cracks appear...especially on a car that sees track time. Because cross-drilled rotors have become a bit of a status symbol, some people have started making dimpled rotors to give that "cross-drilled" look, but still keep the reliability of a stock, or slotted rotor.
I hope this answers all of your questions. My suggestion is this... Take a realistic look at what your car will be used for, and make your decisions based on that. If you are using the car as a daily driver, or daily driver/drag car, then I wouldn't go super crazy on the brakes. If your goal is to build a car that will hold up on a road course, then I personally wouldn't settle for anything less than the safest set-up you can afford.
