This is the best case I have found so far for the LG G3 . It simple , beautiful yet amazing and elegant . I want to share this with you .. I personally find it the most useful case .. so here's the link .. enjoy :
Ottimo LG G3 Wallet Case - caseen
It may be the battery but it may also be a certain issue only with your device . Try sending it to an authorized service and see if the problem persists .
You have made a very big step forward by leaving iOS and joining the Android side . In my opinion you will have many more advantages by using Android than using an iOS . My advice would be to add AVG Antivirus Mobile to your G3 . It will make you feel much more confident about your phone...
If you want to have a simple overpriced phone that has a part of an apple as a logo then you can buy the iPhone 6 . With those money you can buy a much better phone ..