Found someone's phone, where can I find out whose it is?

I found a phone on the sidewalk this morning. An iphone 6 I think. Still works. Where can I make a post about it online or search for someone missing an iphone to see if I can get it back to them? My city has a reddit, will that do?

How often should i switch up my iphone?

I started with the iphone 4 back in 2013, between then and now i've had 2 iphone 4s 1 blue 5c 1 5s and now a iphone SE currentyly i still have my first iphone 4 all the others besides the 4 or SE i still own, cause people are dumb and steal or i lost it… Still how often should i switch up my iphone i got the SE in may, so i'm with koodo, also i find a need for a bigger screen like the 6s or 6, yes their older ish phones but still lol

What's wrong with my iPhone 6?

Yesterday my phone wouldn't hold a charge for very long. I had to charge it at least 5 times so it wouldn't die, and normally I only charge it about twice. I didn't use my phone that much and when I did it wasn't anything that should have used too much power. My phone is updated and I don't have Bluetooth or navigation on, so that isn't draining my power. I also tried to charge my phone a few times last night and whenever I would it would only go as high as 65 percent. I tried different cords and he same thing would happen every time. My phone would also get pretty hot. I plugged my phone in before going to bed and it seemed to be working better, I got up at 3am and saw it was still stuck at 65 percent. I unplugged it and blew into the charge port and plugged it back in, which seemed to help. It charged all the way. Since then I've used my phone a little and it's already down to 20 percent (I stopped charging it a few hours ago). What's wrong with my phone?

What's a good phone that's not too expensive?

I need a phone with a good amount of storage, fairly up to date and fast but something not too expensive around £300 at most £400 at a push. So preferably not Apple because I have an iPhone 6 at the moment and I'm just having more and more problems with it

Which path should I take at 18-years-old?

I'm an 18-year-old freshmen in college. So far I have programmed 2 iPhone apps on the App Store but made no money because I did not monetize them. I have had several salesperson jobs and have taken leadership rules in the past. (sat on a board and founded a club) I just can't decide what to do with my life right now. College does not take up all my time and neither do my jobs, I still have 2 days a week for leisure time (weekends). I can't decide if I should start a retail food company, code more apps, or come up with some innovative tech idea. I'm very bad at coming up with ideas. I do want to be an entrepreneur it is just I have no ideas that are not already taken or my idea will be something super hard and not invented. I just do not know what to anymore.

Added (1). I also have $5k to invest but do not know where to start