I want to get rid of some storage on my iPhone 5

I have a 16 GB iPhone 5s and I've started realizing that I need more storage on my phone. My question is that when I sync my phone to iTunes to see what I need to do to get rid of storage, it says that I have 4.59 GB that is free, but when I go to general - usage (in settings) it says that I have 1.5 GB free. I've synced my phone up multiples times to see if there was any glitch but there seems to be none whatsoever.

Methods for fixing an iPhone five after water damage?

Recently I put my phone in water with my lifeproof case, and the case didn't work in water like advertised and now my phone has water damage. It's been in rice for a few days and improvements have shown. At first my phone was completely unresponsive but now it turns on and there's lines. It's been in rice a few days after it began to turn on and nothing else has changed. Is there anything I could do to fix this?

Any way to get an unwanted person out of your Apple ID?

Ok I don't think there's a way to do this but I ll ask any way. So my girlfriend s family is super nosy and she s not supposed to be dating me. She got a notification that said her brother had joined her Apple ID or whatever. I was wondering if there was a way to boot him off of it. Another problem is that she doesn't even know the password to her Apple ID. Since they re so nosy, they had her other brother set up the account and keep the information. I think the only solution to this problem will be to create another Apple ID to use on an old iPhone that I have. This way the information will all be with me.

Changing from an iPhone 3G to iPhone 5?

I recently got an iPhone 5 because my iPhone 3G is on it's last legs and I'm starting to feel a little sorry for it xD
The iPhone 5 is a hand-me-down from my boyfriend so it has already been previously used.
Anyway, I'm alright on technology but I'm unfamiliar with apple, I've never changed from an apple phone to another apple phone but I'm aware that apple get funny with you using two SIM cards within an iPhone.

So I have a few questions and I'd really appreciate it if you'd try to answer all:
1. Isn't iPhone 5 only compatible with a 'nano SIM' and if so how would I exchange my regular sized SIM to a nano without changing my number or contract?
2. Will my contract cost more per month?
3. How do I transfer all of the stuff to the new handset? Surely iTunes wouldn't work because it's a new account
4. The phone seems to be completely reset but will I be able to create a new apple account?
5. If I create a new apple account can I still connect it to iTunes and transfer the data from my old phone?

I'm really sorry if any of these questions are blatantly obvious or stupid.

My iphone 5s keeps disconnecting from my Wi-Fi?

There's nothing wrong with the router etc or anything cause the rest of my family can get on fine. But every time i try to connect it takes a really long time then i connect for a couple seconds/min and then disconnects. I have to end up "forgetting the network" and logging back in and the same thing happens again.