Should i let my Iphone battery drain to 0%?

My i phone battery last so much. If i charge at morning and check it at night the battery life is still
(90-79%) but is it also ok to let my iphone batter drain till o% some of my friend told me its good to do that.

Is it best to control the volume on my iPhone or on my speakers?

My friend and I have been having a long argument that I'm hoping a sound engineer might be able to solve.

When using a device with a simple auxillary output, e.g. IPhone or laptop, and speakers with built-in volume control - is it best to turn the volume all the way up on the device and then use the speakers' built-in volume control dial or the other way round?

Obviously I'm defining 'best' by sound quality. Thanks for your help guys, hopefully I can prove my buddy wrong!

Jimson xx

Timezone algorithm for software?

I want to create an iphone app to ensure that my children are safe in her hotel/home before I go to sleep at night. One resides in America (UTC-6.00) and the other is in Athens (UTS+2.00). I'm in Australia (UTC +10) = 14 Hours apart. The idea is, they will press a button on their Iphone app before they go to sleep at 10pm their time, every night. So its 10pm, they are about to sleep, they press the button. Before I go to sleep in Australia, I press a "check" button to see if they have checked in so to speak. What is the algorithm that I need to work out for the app so that I know for sure that they have activated the button within the last 24 hours? Do I measure it against the UTC, so +12 and -13? Any help would be much appreciated.

How to put a password in your AirPrint printer?

I'm trying to stop other people in my house in uni from using my printer from their iPads and iPhone etc. Can you put a password on to stop this or is there any other way they can be stopped. (I have asked them not to but they aren't).

Should I jail break my iPhone?

Well, I've been looking online and it sounds amazing!
But I have to take my IOS system back to 5.0.1 or something! (Considering I'm on 6.1.3.). Will I be missing out big time if I take it back to the other iOS system or is jailbreaking worth it?
I was going to use Abstinthe.

Please, only answers from people who aren't ignorant to jail breaking!

Vine app for iPhone 5 won't record sound?

I used to have the 4S and it recorded sound on Vine just fine, but I just got an iPhone 5 and all I hear is static? The mute switch is NOT on, I can listen to people's Vines, but on my own there's no sound… Help? I've even had the switch on the left on audio while recording them and still no sound… Not sure what else to do?

Added (1). I figured it out, it was that the screen protector on the BACK apparently covered a microphone… Didn't even know there was a microphone on the back. But thanks for the help!

Can itunes make a playlist of your iphone library?

I need to restore my iphone and I have a lot of music on it. I know restoring the phone means that non off the music will be saved and I don't want to dig through my itunes library and put all the music back on individually. Can itunes make a playlist based off of the music library already on my iphone automatically?