By pressing the lock button on the top right of the iPhone.
You can't lock your iPhone apps without jailbreaking the phone.
Yes. If you update your iPhone's software using iTunes it will lock your iPhone again. You will then need to unlock it again.
Yes you can but it's not as polished as the iPhone's lock or an Android phone's lock screen. And if you meant does this phone have a "lock screen" when you put it to sleep like the iPhone, no it doesn't
There is no way to do that. If you jailbreak your iPhone there is an app on Cydia that does that.
No it shouldn't, unless you have your lock set to come on after a restart.
jailbreak and download androidlockxt
Yes, by plugging the iphone into your computer and updating the software on it using itunes.
If you bought an iPhone 5s from eBay and it is locked with a fingerprint lock, it will not be possible to unlock it if you do not have the Apple account.
you press the black button on the left size of the phone. it has a picture of a lock on it.
Go to settings general passcode lock set code
I am not aware of being able to "lock" a message, but you can take a picture of the message by pressing the menu and lock button simultaneously and it will be saved in your photos. This works great for saving random cool things that come across your iPhone.