Can I use my sim card?

I have boost mobile as my phone carrier. I ordered a pre owned iPhone 7 plus off the boost mobile website. Can I use my sim card that's in my LG
stylo 4 and put it in my iPhone to activate the phone? Or would I have to buy a new sim card?

Received post from previous owners?

My mum had signed a package thinking i ordered it and opened it and asked me about it. I told her i didn't order anything and then she checked the address and it turns out it is someone who we believe lived here a few years ago. It was an iphone xr which came in the post. What should we do and who do we contact? We do not know the person who it was for apart from their name, btw.

Is it safe to charge multiple things at a time?

I have one of those off the wall charging hub/charging brick/block things and it has 4 charging ports and i just got a new iphone after mine broke and i want to keep it alive and was wondering if it was safe to plug my iphone and laptop/fan in at the same time? Will it cause any harm or should i charge stuff one at a time?

Is my phone broken or does it need to be reset?

My phone was fine until i went to the pool and i think it got overheated and now it won't let me turn the phone off, I can't close the home screen and I can't open any apps by clicking them. If i want to text or go on Instagram or snapchat i have to swipe up from the bottom and go on my recently used apps if that makes any sense. I have an Iphone XR. Did it overheat to the point where it broke? Or do i need to reset the phone at the apple store?

Can an iPhone be on the same family plan that android phones are on?

I've saved up enough money to get an iPhone, but my whole family has androids, is there a way I could get on their plan with an iPhone, dispit everyone else having androids? Should I just get an android phone instead if this is not possible? Or should I get my own plan? I have a job and have never had a phone before.

How can i convince my parents to buy me a new iPhone in about a week?

So my iPhone 5s broke almost over 3 months ago (it stopped charging all of a sudden). Ever since it broke, I have been asking my parents for a new one since then. However, they keep saying that I'm gonna get one soon, but it hasn't even happened. I wanna get an iPhone 8 or XR and I'm willing to put my money towards it as well; but that still doesn't convince them. You see, my old phone actually didn't have service on it because it was my moms old phone and they never put service on it for me (i got it when I was ten). So when I get a new one its probably going to have service; they think that having service on my phone will make me do bad things on it. I have never done anything bad on my old phone or on my other devices. Just because it has service doesn't mean that I will do bad things. They think that I will have too much freedom on the Internet, texting, calling, social media, etc. But that is not true. It is going to be just the same as my old phone but with service. And it is not like I'm too young for a phone; I'm 15 and in 10th grade. I'm homeschooled, so I don't have school emergencies. However, I could have emergencies that can happen when I got to sports practices, and my other activites. And I use my phone to communicate with my friends. Right now I'm currently using my moms phone to talk to my friends, but I don't get to talk to them as much because she is always using her phone for things. So can someone please give me advice or help?

Added (1). I found an iPhone XR on Best Buy and it costs $30 a month. I'm willing to put my money towards the monthly costs. I have told my parents that but they are still not convinced!