Thank you Maldon, it's working now!
Surprisingly all is working already...Wifi, audio, everything...I have installed all apps I needed.
What I just did is Put the EFI after install and then reset NVRAM
WIll figure out the next steps to take...based on your instructions.
This is my first time so I still don't understand what do you mean by things like remove unused kexts, or generate valid serial.
Will reply soon when I get into this.