You may have to turn off model check before upgrade. Read #7 here to try. http://forum.tp-link.com/showthread.php?77915-The-firmware-won-t-update&highlight=Input+command+modelcheck

What's the operating system of your PC? Did you install the driver with CD?

when i try to set up password on "192.168.1.1" site i see password of already existing wifi network of main modem so i cant set up wifi password for my router. On wireless---wireless security page,...

The router will only disaply one network name and it should be the new one. The old one may be someone else's Wi-Fi? Did you remove all network profiles except your new network? Did you try to...

MAC clone is maintained. What's your problem with current firmware? It is better to make a backup of current configuration. Tags is under Post Icons when we try to post new thread.

Provide a screenshot of WAN section on status page of your C7.