this project is to measure power taken by a software when it is running under different loads so it has to measure very slight variations in current and voltages.
since you mentioned current, we are thinking of using a hall sensor IC. the one we are thinking about is acs712 IC. but i think this is not precise enough. can you suggest a different IC for this or mention a better method to measure current.
for measuring voltage can we use a resistor voltage devider to the AC mains to step it down (-2.5V to 2.5V), then use a linear optocoupler to isolate the 2 circuits and shift the sinusoidal wave 2.5V and then give that to the PIC. will this work ????