All answers here, while probably universal, are stated for the Caibo EB- series


Can i emulate the code without my final pcb design ready on the emulator?
yes
where should I download the HEX file while using emulator without my final target board.
The software that comes with the emulator takes care of that
where is the microcontroller(the one i will be using on my target board)present ,on the emulator board or some different module(board)which the emulator supports for a specific family
on the emulator
Is it possible for me to add periperals (like display ,a/d converter)from the module where the microcontroller is present using the i/o ports.
you plug the ICE into your board and it will drive what is on the board exactly the same way your final chip will.
many low cost emulators have background debuggers .how much resources (code,data,i/o ports,interupts)are consumed by this background debuggers and wont it block the exeution of my actual code.
Ceibo 'consume' a wee bit of code space (top of 64k) and two slots on the stack, no timing overhead, the only blocking of the execution will be if you set a breakpoint.

For a good comparison of emulation technologies there is a good article at:
http://www.ceibo.com/pdf/Technologies.pdf



Erik