How does an international SIM card work?

I'm going to study abroad this semester in England and I need help deciding what I will do about my phone. I have an iPhone 5 and I want to use that when I go abroad. I was thinking about changing out the SIM card instead of paying international fees, so how do SIM cards work? What will I have to do before I leave and once I get there? And I'm confused about whether or not my phone is locked.
Also, if I get a new SIM card, what will be saved on my phone and what won't appear unless I put in the old SIM card?

Help FBI WARNING ON MY IPHONE?

I was browsing on my phone and an fbi warning popped up, telling me to pay a 500 fine or my phone will be shut off. I can't get rid of the virus on my phone. If I get out of safari it keeps popping up and I can't do anything. SOME Please I'm NOT CALM RN. How do I get it off my phone without using money?

What is the better way to protect your Iphone?

1. To get a tough protective case that is water proof and has a built in screen protector and stuff, or
2. Just to get a really tough case and a shatter proof screen protector?

I want to make my Iphone last as long as possible and be as heavily protected as possible.

I don;t know which option would be more protective.

Because with option 1 i'm geussing the screen protector for it isn't going to shatter proof, i'm not sure, but it will be waterproof.

and option 2 will have a shatter proof screen protector but would not be water proof.

which is better? Which is the better protection?

Siri/Voice Control keeps activating itself and popping up out of nowhere. What do I do?

Siri/Voice Control keeps activating itself and popping up out of no where and it's starting to irritate me. I don't even have the phone in my hand and Siri activates itself telling me that it didn't hear what I said. I got annoyed so I turned off Siri. After that VOICE CONTROL started popping up. Then it starts playing music from my playlist or it takes itself to the multitasking part of the iphone. I even tried turning off my data and it still pops up. It's irritating me and I just want it to stop. Is there anything I can do? I already tried turning it off and on.

IPhone Vertical Video to Youtube?

When you're a dumb and record a video vertically, on the iPhone you can double tap to zoom in and it's completely fine. However if I were to upload it to youtube it would be zoomed out, is there anyway to recreate the iPhone zoom in as some sort of cropping?

Where can I buy an iPhone 6/6 plus clone in Toronto?

Where can I buy an iPhone 6/6 plus clone in Toronto?

Added (1). My iPhone was stolen and need a cheap and quick solution. So where might I be able to buy an iPhone 6/6 plus clone in Toronto and York region area?

How to add music to an iphone?

I have an android and my cousin has an iphone. I add music to my phone by connecting my phone to the laptop with a USB or SD card.

My cousin buys music on itunes, but she gets annoyed that she pays for it when i can get music for free. She asked me to put music on hr phone the way that I do, but when I tried it wouldn't let me copy the files into her phone.

What's going to happen if your out of cellular data?

I have an iphone 5s i recently got out of bell and move to Wind mobile it says everything is unlimited i have unlimited data, texts or calls my dad says i can use it as long as i want but what will happen if i run out of data?

How to use my Verizon iPhone 6 in New Zealand for 7 months?

How to use my Verizon iPhone 6 in New Zealand for 7 months?

Added (1). So I'm going to New Zealand from the US for 7 months, I have an iPhone 6 and my carrier is Verizon.
I'm planning on suspending my account for the time needed, but I have heard that by getting a SIM card that is compatible with Verizon can still use my phone there other than just on Wi-Fi.

I was curious if anyone knew if any of the carries there are compatible with Verizon.

I don't leave for another month, but its just something I want to be prepared for and not have to pay a lot for either.