Hey Don!
1) Best / easiest way to root would be:
I would have saved myself so much hassle if I had just found this post
before I rooted my N7.
I've rooted every android phone I've had
but I'm no expert or dev dude. Not a novice either. But anytime the command line gets involved i get squeemish. Each time I've been able to do it I've based my success not on myself but on the people who write the how-to's on forums like this. For me, one of the best things ever was the advent of the one click root apk's. I've avoided having to use my computer to root a phone... until the other day.
To make a long story short, since I live in the margins anyway as it is I figured I'd give kingroot a shot... knowing ahead of time that it's a suspect product... unfortunately it's one of the only way to successfully root my phone... a LG vs810pp (transpyre). Much to my surprise, it worked great. The first time! Then I ran a script I found on xda that replaces kingroot with SuperSU. Once again, worked great. First time.
Emboldened, and knowing that google is done sending OTA updates to my N7(2012) i figured now would be a good time to root it. I didn't have a lot of the problems that many people seemed to complain about regarding 5.1.1. but I figured it couldn't hurt to get rid of bloatware and get some control over the tablet.
Kingroot worked fine... But when I ran the script to remove and replace with SuperSU all hell broke loose. Got the bootloop. But I didn't panic.
I came here and found this thread and also used scary_alien's guide regarding flashing the stock image on a N7. Then I used the guide on this page to get root back. So 8 hours later after a few failed attempts and thinking I had a hard brick... I got it to work and was back up and running. Or so i thought. According to the tablet I only had 6GB of storage space. Doh! Did a factory reset and that fixed everything.
I said all that to ask this... After I did a factory reset I went back into recovery mode and noticed the instance of TWRP I installed when I rooted the tablet is gone. I still have root access, just no recovery program. Can I just go ahead an install TWRP from the play store? Or do I need to flash it again via fastboot?
Special shout out to scary_alien for saving my arse not once but twice! Great how-to's dude. Very detailed and accurate. Thanks $1,000,000!