IPhone 4S randomly turns off.possible water damage?

I'm just wondering if there's any point in trying to fix my iPhone. For a while now it would randomly shut down. I then noticed the battery was draining quite fast. I made the mistake if changing the battery myself. Now it's much worse. I took it to Apple and they won't do anything because I opened it. They noticed (and I noticed) it looked like there was water damage up top in a screw near where the camera is (probably from my cat knocking water over on it). After changing the battery it now shuts off if I use the camera. I'm just wondering if there's any point in fixing it, or if I should just bite the bullet and get a new phone?

Does it charge if someone calls me from the US?

I've got a family member and friend who are currently living in the Usa however I'm in the uk and I was wondering if they call me would it charge me and also them? Or it will just charge them? I've got a iphone 5c EE network phone I currently don't have any credit on my phone however if someone calls me I can still answer I was just wondering if its free if someone from the us calls me if I'm located in the Uk.

Added (1). I don't want to use Skype I'd rather use mobile phone. Please read what I just said because I didn't mention anything about abroad I was wondering if I get charged from an incoming call from a person who is in the Us and I'm in the uk. So they will get charged if they call? No matter there location?

Is an iPhone a smart choice?

My phone broke last week, and my plan is eligible for an upgrade. I have unlimited data/messaging, etc on the plan, and I wanted to get an iPhone 4s because they are very fast and I have never seen one force close (My last Android phone had a problem with that). I keep hearing that even if you have an unlimited data plan, the iPhone still has a data limit that you can't go over. If you do then you have to pay a fee. Is that true EVEN if I have an unlimited data plan? And is there any hidden/monthly fees I will be charged for just from having an iPhone?

App that hides a second app, does it exist? (Iphone5)?

I'm looking for an app where I can keep hidden certain apps I don't want others to see, I've looked everywhere but I could find apps just for notes and photos.

I've already seen the trick where you hide an app but it still exists, but that's not what I'd like to have:/

What happens after incorrectly entering a PUK code 10 times?

My sister brought home an Iphone 4 or 4s from work a couple years ago after no one claimed it. I never touched it until now just looking through it. Well the Sim is locked ofcourse and there's no password on it. All I want to do is play games so what would happen if I put in the wrong PUK 10 times? Can it erase everything? Will it notify the carrier? Will it entirely lock me out? What happens if I factory set?

Ebay case help escalating the case?

I have an opened case about and iphone 5c which had to be unlocked but i received the iphone locked to att, and i tried contacting the seller but he seems to be no trying to help. So if i escalate the case and i guarantee that i'm right and i uploaded pictures showing the phone locked. What happens if the case has been escalated? Like what can happen? Will ebay refund me or something?

Alarm dock for both iPhone 4s and iPad 4?

I want a new dock for my iPhone, iPod and iPad as the one i have is old and starting to break. I have a iPhone 4s and iPod 4th gen, so they both have the older charger, I have now also got an iPad 4, with the new charger, and I'm wanting to get a dock that can charge all three (it does not have to be all three at the same time, just one at a time will do.)

On the dock i need an alarm (would be good if it had two alarms), good quality and loud sound for playing music through iPhone/iPod/iPad. Changer for iPad 4 and iPhone 4s If there isn't any good ones with both chargers i would prefer the older one (iPhone 4S/iPod 4th gen). I'm not too bothered about radio as i have most off my music on my phone but if it has one then that's just a bonus.

My price range is about £50-£100, i would be OK going a bit over £100 but would be best if it its around £50.