DanYal

Not possible , Only Jb devices

What do you mean by blue screen ?

Install Cydia impactor from Cydia and It'll unjailbreak your device after that you can jailbreak your device again

Install crash reporter from Cydia or open activator and go down to assignments and check what did you set gesture

Install uicache icon from the cydia and reboot

Install it from here http://iosgods.com/topic/6014-icleaner-pro-v744-compatible-with-ios-4x-–-8xx/page-1?hl=+icleaner%20+pro And just clean your iphone

It won't , give it a try

Ow Make sure you uncheck the Cydia sources and then go to + and go down and open preferences file and look for that and delete the preference , then clean your iPhone and respring , install the hack and respring

Good

Delete the hack and use icleaner and respring Now again install hack and respring

use vpn

Un-install what you install for this app , use icleaner and respring then try

i don't think so their is a app like this or any tweak

Server sided , Not possible

& sorry you can't downgrade your idevice to iOS 8.4 , Apple not signing anymore iOS 8.4

Get a background manager tweak from cydia , Watchdog pro or dissident

Not possible for non-jb

The boy said it is 80gb

Lemme see