Soft in GT-I9301I

Hi, I am new here, i have a few questions.

I want to change my soft in GT-I9301I. My plan is:
1. Do a root: http://ift.tt/1oH5P5Y
2. Install TWRP http://ift.tt/1zFS9Jm
3. Do nandroid backup.
4. Install ROM http://ift.tt/1LIpn3T
5. Repair battery https://www.youtube.com/watch?v=FPMneDKqyOc

I won't brick my phone? I have phone with I9301IXCUAOF1 soft. If my phone brick, can I use nandroid backup? Is KNOX is in this phone?

Thanks for answers. Sorry for my language, i am from Poland. I don't speak english very well, but i never use Google Translate ;).

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