Hello, I'm in the UK and I'm facing a problem similar to yours.
I got my device at the beginning of December, and used to get ~8-9 hours of screen time. Now, I'm barely getting 6, and you can add screen lifting and back light bleeding issues to that as well.
I'm going to preform a factory reset in a few days, if that doesn't work, I'm considering getting it to customer care/replaced.
PS, I'm stock 4.2.1 and my Wi-Fi doesn't turn off when it's in sleep mode. :-\
Sent from my Nexus 7
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