Need help with some questions and advice about restodudu

[fluttershyxd 3]

Hi everyone! In the middle of highmaul i had to reroll from resto shaman to restodruid.. I played alot of restodruid in cata and early mop but i still think i need to improve. 

My questions are pretty simple but its still some things im trying to figure out.

1. How worth is it to use mushroom as often as possible on fights where the raid is spread? Iron maidens for example.
2. Im a big fan of incarnation: Tree of life, is it bad of me to use it instead of Soul of the forest or is it more of a choice?
3. Which bosses are you usin dream of cenarius and which bosses are you guys switching to Nature's Vigil?
4. Why are some people glypinh Rejuvenation? is it worth it? 

Im also gonna show my logs from yesterdays raid ( i got oneshotted on flamebender and died cus bad on hans..) because even if im doing decent im struggling abit and feeling like im doing something wrong.

https://www.warcraftlogs.com/rankings/character/7316408/latest/

http://eu.battle.net/wow/en/character/frostmane/Peys/advanced