Google Nexus 7 (2013) — Senior needs help with rooted Nexus 7(2013) and lollipop update

Please help and please be kind and patient with this senior citizen.
I have a rooted Nexus 7(2013). It is rooted at 4.4.4.
I saw the released Android updates to lollipop that I want to use and I need help with the procedures as I have to deroot my Nexus 7 first?

I assume that to update to lollipop, I would need to:
- Backup using Nandroid
- Deroot my Nexus.
- Go to the Android site, then update to the latest version of lollipop.
- When the upgrade if over, then re-root.
- Even, though I was able to root my Nexus 7, I have forgotten many of the specifics.
- Please help guide me as I think I need to:
- Backup my Nexus 7 – I have both Titanium Backup Pro and Nanroid Backup Pro

Should I use Nandoid Online backup to restore
- Nandroid Settings - Please help me with these Nanroid settings aftger selecting Custom Backup.
- Backup Name – UTZ Timezone
- Type – TWRP or Clockworkmod – I assume I select TWRP
- Normal Backup Mode?
- Do I select any of Yaffs2 as Tar or Exclude Dalvik Cache, Exclude Google Music Files.I have to admit, I have no idea what Dalvik and Yaffs2 are.
- Move to TWRP backup to my PC because it winds up being about 3gb and I haisve a 16gb Nexus 7.

This is where I get very confused. What exactly do I do and use start the derooting? Should I use the WugFresh(1.99) toolkit?
After derooting, I should NOT restore anything. I do an upgrade of Android to lollipop.
After my Nexus 7 is lollipop, I would need to do a recovery/restore of my Nandroid backup??

I have the following products that might help:
-Titanium Backup Pro
- Nandroid Backup Pro
- BusyBox Pro
- SuperSu
- Root Checker Basic
- NoBloat Free

Thank you for your time, expertise, kindness and patience in advance
Jon