Bought a rooted phone? topic

Hey guyss, so i just bought this awesome phone on craigslist and it is already rooted and idk if the guy did anything else beside that ,so is there a way i can check everything like firmware, cid, and all the stuff ?

And also , do i need to convert to gpe if i want to install lollipop roms like SkyDragon gpe , blisspop , or cm12 or do i just need to flash it through recovery?

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