Is this possible to backup settings inculde derpQuest and UI? if yes how to restore them? Thank you.
Can't tell you exactly. Seems, it's impossible.
Moreover, restoration of such backup may cause a ROM issues.
If you want to install an updated build, just dirty flash it.
But will this cause any bug? Or error?
Dirty flash is not so good as a clean flash. So, some issues may be related to it. Nevertheless, I use a dirty flash on my device and have no issues. I'm using MSM Xtended ROM.
Create a backup in TWRP (System, Data, Boot partitions) and try. Anyway, you'll be able to restore the previous version with this backup.
**** Disclaimer: I'm not responsible if you destroy your device. Use at your own risk!!! **** NOTE: I allow off topics in my thread. I'm also open for any fun. Discussion about ROMs is permitted as far suggestions. However what isn't tolerated is belittling of devs and or their work. Thank you. :)