4 Easy newbie questions ;)

Hello!
Here are the questions:
1. Is the bomz accesories good? because I have seen some CAI, exhaust, etc. at very low prices.

2. What does the AEM fuel rail do on a stock engine, is it worth buying?

3. Does anybody know where can I buy the little squares that are next to de head lights?

4. I'm planing to buy a couple of autometer gauges. What gauges are worth buying (air fuel ratio, oil presure, oil temp, voltimeter, water temp, water presure)?

5. Is there a difference between a DC Sports Headers and some generic headers? Like Hp racing?

Thanks guys!
Im waiting to leave my car as I want to put some pictures on the forum