1.I would like to know if i can use the At-mega chips programmed from Arduino can be setup into my PCB, if yes do i have to obtain any licence from arduino community?
Yes, you can. You don't have to obtain a license.
2.I want to use my own custom components (like sensors or Motors ) in my self designed PCB and use the chips programmed from Arduino as the processor for it with the help of the external sources like the oscillator and power supply( which is not intended to do any replica of arduino boards) for functioning say like want to sell a product which turns on the light of room based on some PIR or IR sensors. i would use only the functionality of the At mega chips as specified by its data sheet and use the boot-loader and lib's and the program from the Arduino to make my product and sell it in my own registered name.
Please advice/Suggest as it would be a lot helpful. Thank you smiley
Yes, you can. You can even replicate the boards and sell them as long as you don't include the name "Arduino"
.The arduino software and hardware is open source. But the name "Arduino" is trademarked. As long as you don't use the name "Arduino" you're fine. That is why clones use names with "Duino" in the end like "Freeduino". If you use the name "Arduino" for your product it'd be illegal.
I forgot, the logo is also trademarked. Don't use it.