Trouble installing windows (USB, DVD & Windows Upgrade)

i've been having lots of trouble installing Windows 8.1 on my ideapad z710 laptop, so here's what i did..

1. i downloaded a Windows 8.1 Enterprise ISO from "http://ift.tt/1PAhCti"

2. i burnned it to a dvd using the slowest possible speed and than i went to my BIOS switched to UEFI only But my optical drive was not being detected i switch it to legacy support and the optical drive was there but when i tried to boot from it it freezed at POST for about 5 minuts and than wen't straight to my bootloader.

3. than i decided to try USB i formatted my USB to FAT32 Flaged it as bootable an installed the ISO with "Unetbootin", than i booted the USB and the setup screen asking me to configure my locales and keyboard started up but when i click Next>Install i get the Message "A media driver your computer needs is missing" inserting a DVD with the drivers won't work as it doesen't get detected (The USB is NOT in a USB 3 port, and i tried changing ports and unplogin every peripheral device like mouse ethernet cable etc..).

4. than i decided to try to upgrade from my currecnt Windows 7 installetion so i inserted the USB run the Setup and than i get the message "we can't tell if your pc is ready to continue installing windows 8.1. try restarting setup"...

Current Setup: Linux & Windows 7 dual boot with GRUB...

i want to upgrade OR clean-install windows 8.1 in place of windows 7, i have tried everything i can think of and i can't get it to work if you have any suggestions please tell me

A solution to any of this three problems would be much apreciated, thanks in advance...

PS: i'm willing to try ANYTHING :p