Just an update on my sensor project. Actually while I was trying to tinker with my multiple sensors with pi zero, at the same time I learnt about the ESPEasy firmware. So, paused for a moment and went for a quick testing with my ESP12E board lying idle in my electronics repo. And to my wonder, it was decently easy with this firmware to setup multiple sensors within no time.
Though initially there was few hiccups related to MQTT but later I figured out it was simply a case of the firmware version. After I choose the right one, it was damn easy. Now, as expected my little made custom box is reporting Temp/Humidity, Lux in 10mins interval and sending alert as soon as motion is detected. Happy me 
I do have plan for enhance the efficiency of this thing by adding some more sensors; probably Smoke and Gas detection would be the next line of fire.
If anyone is interested on the ESPEasy with ESP nodes, here is an interesting thread.
Thanks & Regards
Tarikul