Important question about snapchat photo quality

This has been bugging me for a while. Whenever i upload a photo from my camera roll to snapchat, it always comes out really blurry. But whenever my friends do, their picture turns out in really good quality. At first i thought it was because they all had iphone 7s and i had the iphone 6S. But i just got the iphone 8 and i'm still having the same problem… Why. Are my camera roll pictures blurrry when i upload them? Can someone help me out please?

I keep getting pop-up ads on my phone?

Okay so I was trying to download an app that I wanted, but I download from a website on my phone, but now I keep getting pop-ups ads in my phone telling that I won an amazon gift card or an IPhone X. I know for a fact that I've download a file instead of a App, and have tried to delete through the settings apps, but it doesn't let me delete any flies, only apps.

If you know how to delete files please let me know! I appreciate if you do comment, though.

What will happen if I got caught doing this?

My phone contract had recently ended and can't get new upgrade as its v, expensive! So I have to stick with this broken iPhone for another year! However I feel angry that my mom won't let me upgrade and I really want to use my moms cards and details to secretly buy a new phone contract. So what will happen if they find out that this isn't me?

Why is the Wi-Fi on my iPhone always getting weak signal?

I recently swapped phones to an iPhone 6 from an iPhone 5, and i noticed that where i would usually get Wi-Fi around my house on my iPhone 5, it was no longer reaching my iPhone 6, i compared it tom brothers who also has an iPhone 6 and put them next to each other and he was getting 2 or 3 bars of Wi-Fi whereas i was only getting 1, i would also be right next to the Wi-Fi box and still be getting max 2 bars, this is super annoying because i can't get Wi-Fi in my bed anymore, bare in mind this is a second hand iPhone so it could be possible that the person before me dropped it or something like that and the Wi-Fi thing in the phone broke a bit, but i have no idea really, I'm just putting out a theory, it would e greal if someone could help me how to fix this.