How to properly place AC current transducer sensor in the circuit
simulate this circuit &ndash; Schematic created using CircuitLab

The normal industrial approach to this would be to monitor the incoming supply (AM1) and (what you think are) your major loads. The remainder can be calculated as AM1 - AM2 - AM3. You can then decide to add additional monitoring or move the monitoring from one circuit to another.

Monitoring both live and neutral is pointless.

I suspect that what you are planning will be largely a waste of time and money as much of the consumption will be fixed. For a while I monitored my house's energy meter using a photosensor looking at the spinning disk and logged the pulse count every minute. After a few days, I was able to identify the kettle, water heater, washing machine, oven (hurry home from work!) just from the chart. All that with one data point. It was actually a little creepy how much I could infer about activities at home from the information collected.

To answer your questions:


  In setup A, Is it okay to put the sensor either in the live or neutral part of the circuit? 


Yes.


  So sensor X and Y should read the same value. The same goes for 1 and 1B,2 and 2B, 3 and 3B.


Yes. So why measure twice?


  Now setup A would waste a lot of wires if the three devices are close to each other but the distance back to neutral is far. So in setup B i joined the neutral while they were still close to each other and run only 1 wire back to Neutral line. 


That means rewiring the mains circuits in your house. Probably not a good idea.


  Is this setup still okay?


The common neutral would have to be sized to carry the sum of all the circuit currents.