Unhappy [Q] xperia ZR c5502 . need some help

hay people , I am new xperia phones users and am looking for some answers but i can't get it !! so if u have a link to any thread include the answers that i'll ask just but it in a comment or answer me plz
i am sorry ( bad english )

1. what is tha TA backup !! what it's means and how can i do it ???
2. how to flash stock roms and where to find it for my xperia ZR c5502 ??? and what is the flash tool and how to use it
3. how can i but the phone back to the warranty state
4. what is the mean of fastboot and what i'll use it for ??
5. when i flash a stock rom how to get into recovery and make a wipe for data and cache ??

that's all i know that i had a bad english and i know that i asked alot but plz help me thnq