Asking for some suggestions topic

I just bought one Nexus 7 for a relative at oversea, who has zero knowledge about rooting, bootloader, recovery, custom ROM/kernel, etc. However, I want to root the device at least, to install some good apps like Xposed framework , greenify ; yet do not want to prevent OTA by the owner himself later if he wants to.
So, is there any app to retain root if OTA ? And any other tweaks you can think of ? TIA