I do not know the inner details of the sensor at (4) because the producer's site is awful!! I was not even able to find the data sheet of the CR9500 series on their site!!!!
BTW, if you refer to the first .PDF in the data sheet: **broken link removed** you will see how to connect your sensor...
Maybe the connections will be different (wires instead of screws) but the result will be the same.
1) Yes, you do not need to power your sensor. This one is the reason for my doubts of its linearity at very low loads. You did not say what are your requirements regarding precision/lowest_value/highest_value you want to read, I'm not sure if this device is the correct choice.
2) Yes. You have to read this voltage with an high impedance input (> 1 MOhm): by default the typical input impedance of an ADC on a micro is about 100KOhm, so you will need to buffer the output voltage, otherwise your results will be wrong.
3) The output value of the sensor is proportional to the MEAN of the RMS current of your load.
Example: you are using a 20Aac full scale sensor; its output at 20Aac is exactly 5.0Vdc.
If the load is 10Aac, the output voltage will be 2.5Vdc (5V/20 * 10)
If the load is 2Aac, the output voltage will be 0.5V (5V/20 * 2)
If the load is 100mAac, the output voltage will be 0.025V (5V/20 * 0.1)
If the load is 10mAac, the output voltage will be 0.0025V (5V/20 * 0.01)
I'm assuming you are living in the USA (CA), so your mains voltage should be 115Vac. If you want to measure very low loads (1-2W) the output voltage of your sensor will be VERY low (few millivolts) and you will have troubles to measure it correctly!
Please also remember that measuring the current of a load does NOT require to know its supply voltage!
Only if you want to compute the wattage of the load you have to know the supply voltage.
Unfortunately, as I have already wrote, I really do not know your exact requirements (precision/dynamic/...) so it is a bit difficult to try to help you...