Fixing iPhone 5s that doesn't turn on (likely water damaged)?

My friend bought an iPhone 5s online but figured out it does not turn on nor does my computer detect it (tried home+power button at same time just in case and nothing). The previous owner did not say anything about it being damaged but I figured most likely it is water damaged. Is there any way to diagnose the problem and maybe fix it?

Why do my hands always catch on fire whenever I text people?

It's the freakiest thing ever! I don't know if I should see a doctor or what. Only my friends and family know about it. They have no clue why it happens. My mom wants to take my phone away from me so it won't happen anymore but I can't live without my phone! I only got burned badly one time and there's a little small scar. But it's So scary when this happens to me! I'll be texting (it usually has to be for a long time though) and then while I'm holding my phone my hands suddenly catch on fire. I have an iphone 5 by the way. I even tried washing my hands before texting. I don't know what to do anymore

What file type do Instagram uploads need to be?

So whilst I was climbing in the Alps last week I took some photos using a Lumix as I didn't want to drop my iPhone, and I've been trying to upload them onto my instagram feed. I've attempted to sync from the Photos app on my Mac to my phone but couldn t get it to work, so I exported the files to my desktop and transferred them that way. However, I converted them to JPEG format and now when I go to upload they don't appear in the camera roll. I assume this is due to them being JPEGs and not the correct file type, so what file type do they need to be?

Best Buy Phone plans for an unlocked iPhone 5s?

I work at best buy, and I know you're thinking that I should know this but I really do not keep up to date with phones that much. I work in best buy warehouse and I was curious to see kind of plans I can get at a good cost with my employee discount. Right no I have a T-Mobile pay as you go plan that runs me about $30 a month. I would like to have unlimited text/call with some data at a good price. I'm not sure what carriers give as a discount especially to someone that doesn't work in Mobil. Once again, my phone is unlocked.
Ty for your help!