Opensource .. confusion ..
 

I am new to development and Linux.. I need the following answers..

1. If Linux is Opensource, why each company is developing their own APIs, Took Kit and Development Platform? I feel real Opensource is the base code and these companies use to make their own propreitary applications.

2. In Android Mobile, is Linux does Linux replaces the traditional RTOS like Nucleus etc to develop Stack? Is Linux capable of giving the performance and scheduling of RTOS?

3. Please tell me how to start developing the applications, compiler, tool kit to download and software, IDE etc needed to develop the software? Debugging tools etc? If i use Linux, how to get BSP, Drivers etc in Linux compatible to linux code?

4. If Linux is opensource, why each company came with their own APIs etc and ganged as Android,Meomo, Neo, Qtopia etc? Along with community based Linux like CE, GNOME, LIMO etc..

Thanks in Advance.

Duplicate--reported for closure.

Closed per above.