What is wrong with my Instagram?

So, my sister and I both have an Instagram, She recently got an iPhone 4 in August 2012. She downloaded the Instagram app and logged into her account. A couple days later I logged into my IG account on her phone. From then on she keeps getting my notifications and hers. I got an iPhone 5 in December and logged into my IG account hoping this problem would disappear. It still hasn't. She gets notifications when my Facebook friends create instagrams and she gets notifications that they follow her. I think it's weird how all of my Facebook friends are following her Instagram and not mine. Is this a problem with Instagram or Facebook, cuz I also logged into my Facebook on her phone around the same time. Is there anything I can do to fix this? This problem has been going on way to long!

Clean install of the iOS on the iPhone?

Is there a way to do a clean install on the iOS.
I'm an iPhone owner for one year and I've reinstalled the software a few times but everytime I ran the backup from iTunes.
Now because my mac is slow as well I want to do a clean install of the OSX Mountain Lion and also a clean install of iOS as well on my iPhone. I know on OSX it is possible but is it possible on iOS?
Thank you!

Added (1). Ok so If I reset and don't use the back up how do I get the apps without paying once more for them is there a way to see the apps that I had and choose from them which one I want to keep which one I don't?

My IPhone was dropped in water?

Today, i tried to check the time on my phone, and the screen sort of flitted and then turned off again.confused, i tried again, this time the flicker had a super low light. After i while it just didn't do anything at all. So later my friend confessed he dropped it in a sink, and it was fully submerged for about a second. Should i still try the rice method?

HTC One vs Samsung Galaxy S4 vs Iphone 5?

I'm going to be upgrading my phone. What do you guys recommend? I'm leaning towards HTC one because i heard great things about it and not many people have i which i like. Please give honest opinions and try not to be biased!

Iphone help? Thats been wet?

My i phone went into the washing machine. I dried ut out but want to know can i get all the info back even thought it starts up and is blank? I have old text messages on there someone sent to me and i need them for a court case

Why is there so much other on my Iphone?

7.89 GB of storage on my phone is taken up by "Other". I've tried restoring it, sorting through apps, everything that i can think of; but it isn't fixing ANYTHING. Please help, i can't even take pictures anymore due to lack of storage.