Hello McCarra! Thanks for compliments and for your answer!

You both need a team understanding you, and to understand your team! That's the key, and that's why constructed teams can rely more on Tyrande.

Try it, but never ever forget that you have to adapt to the situation, according to the way you will play and the way you will pick your talents. And try the common "Owl build", keeping in mind mana issues if combined with Battle Momentum.

Hum... That's a really difficult question to answer. Themselves, maths behind this could be simple, but you have so many assumptions to determine: the talents, your AA uptime, the abilities your land before using Rewind,.. Then you have to determine how many people are hit by Sentinel and Lunar Flare, talents depending of this abilities,... So,... I feel like there are too many possibilities to assume a unique right calculation of what you are asking for.
Therefore, I can give you some tips that could help you to make your choice.

-Would it be Nexus Frenzy or Rewind, it won't be decisive in your global playstyle. Keep that in mind: you decide how Tyrande is to be played.
-There are two different kinds of impact. First, the "overall" impact. Nexus Frenzy gives you more global cooldown reduction thanks to Battle Momentum (1.5 Attack Speed instead of 1.25 ; 2 with Huntress' Fury) and also more overall damages. On this side, Rewind brings almost nothing. Second, the "team fight" impact. In addition to what i said previously which applies here too in a way, you will be able to play safer thanks to Nexus Frenzy's range you should feel more confortable in fights because of the range but also because in HotS you shouldn't be a turret, but rather attack/move/attack/move/etcetera, and attack speed add confort to that. But there, Rewind brings a lot. Imagine two consecutive stuns and owls (you don't pick owl's talents but trust me, an owl with Pierce/ Ranger at level 20 is devastating) plus an extra healing is something massive in fights. Though, as I said about Rewind in the guide, it has to be done properly, i let you check it once again if you don't see what I mean here.

So, to sum up, I'd say that if you look after that significant burst (in damage, yes, but in utility as well) in fight, Rewind is for you! Still that it recquires practice and concentration. That's the point: if you are confident in your micro, feel you wanna concentrate and give the more you can to your team in fights, Rewind is better in my view. If you just want to let your brain apart and play a soft Quick Match, Nexus Frenzy does a good job!
So once again, it is up to you, like many things on Tyrande!

Give me news about it! ;)