Install BetterBatteryStats and see if there's any wakelocks that are eating your battery at the moment.
Also, about your on screen time - what's the settings for brightness that you use? You might want to consider dropping the "auto" and go for a reasonable low level of brightness that fits your indoor or outdoor activities.
Your assumption of WiFi eating less batter than data connection is correct in most of the cases.
Anyway, if you have any doubts about this... an average NOTE3 user can't get to those 3h 30minutes with on screen time
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MOTO G - STOCK 4.4.4 - ROOTED + XPOSED + Greenify + Faux's Kernel.