Iphone frozen on slide to upgrade, ios 9

So i tried to download ios 9 on my iphone 4s today but it got frozen on the slide to upgrade. My computer said that it needed to update to itunes 12.3 so that it would work with the ios 9, so i updated it but my phone is still broken. Online it said to restore it from itunes but itunes said i needed to turn off find my iphone using my phone, which i can't because my phones frozen. So people said do it online which i did from icloud.com but it still doesn't work. Also if i try to sync my iphone it gets frozen on step 2 of 6.

Should i update my iphone 6 64gb to ios9?

I got a lil phobia of updating phones, anyway is there chance my phone could get slow? After updating to 8.4 it already showed problems (notification/control center often became un accessible). Is there anyone who is having troubles with his/her iphone 6 running ios9?

Jailbreakers - Is this possible?

Jailbreakers - Is this possible? - 1

Added (1). I recently bought an iPhone 6 and luckily enough it only has 8.3 installed. My previous iPhone has 8.4. To restore from backup, is it possible to download the iOS 8.4 software and update or if I attempt this will it force me to upgrade to iOS 9.0 which is unjailbreakable as of now.

Will my Contacts, pictures, apps get deleted if I upgrade iOS 9?

I'm trying to delete stuff to have more space so my phone can get backed up. I have an iPhone 6 but it doesn't have a computer connected to it. I don't want to have it say that I have to connect my phone to iTunes when IIm updating. So will my stuff get deleted? Even if it's backed up on iCloud?

My iPhone 5s was water damaged and I can't back it up. Any ways to fix this?

My iPhone 5s was badly water damaged this week. It won't "turn on" unless it's plugged in, but even when that happens the apple logo flashes and nothing happens afterwards. When I would plug it into my computer to try and back it up, iTunes would start but then it would say "waiting for phone" which was a problem cause I couldn t do anything. So I replaced the battery on it (so it could have a charge since my phone doesn't seem like it's charging anymore) to see if that would help but now when I plug it into iTunes it starts to update to iOS9 in order to back it up. The only improvement with the new battery is that when I start to back it up the iPhone updating screen shows up, but then iTunes says error 27 and gives up.
I haven't backed it up in months and have a bunch of stuff on it. Any help or ideas would be great. Thank you (also IIm trying to stay away from the website that you have to pay $60 to recover data from your phone)