You have your cases listed under Motherboard and Motherboard listed under cases.
You have a Intel processor chosen, but you're looking at Motherboards with AMD sockets, except for the Asus P8Z68-V PRO/GEN3. The other motherboards will NOT work with the i5-2500k or any other Intel processor.
Consider choosing a better HDD brand like Western Digital. I've owned 3 Seagate HDDs over the years and all of them died within a year. have 5 different WD HDDs ranging from about 1-6 years old and all of them are running like new. I will never buy anything other than WD for a HDD again. SSDs are a different story. There's a reason Seagate drives are so cheap.
To install Windows after you build the PC you are going to either need a DVD drive and an install CD or you could create a bootable USB. When you boot it for the first time, you need to choose which device to boot, boot from the DVD or USB, and then follow the installation wizard.
The Asus P8Z68-V PRO/GEN3 will fit in any of those cases.