8.32.3 Can you answer these questions?

8.32.3.1 Detect \end of an environment

https://tex.stackexchange.com/landing/r/digest?cta=question&id=644652

I'm trying to create a macro that grabs everything till the end of the current environment and parses it. At first, I just want to put ! right after my macro and another one ! before the end of ... 
[macros] [expl3] [latex3] [arguments] [parsing]
 

asked by antshar https://tex.stackexchange.com/landing/r/digest?cta=user&id=213149 Score of 1

8.32.3.2 \underline and \underbar commands have change warning

https://tex.stackexchange.com/landing/r/digest?cta=question&id=644066

I have two warnings telling me that "Command \underbar has changed." and "Command \underline has changed." but I don't get why is that so since I am not using these commands. 
I ... 
[warnings] [underline]
 

asked by RubA~(c)n PA~(c)rez Sanz https://tex.stackexchange.com/landing/r/digest?cta=user&id=195186 Score of 1

8.32.3.3 Margin when using auto-scaling of parenthesis: Is there a better way than adjusting for it with "\!"?

https://tex.stackexchange.com/landing/r/digest?cta=question&id=644467

Whenever I need larger parenthesis I use \left( \right) which automatically adjusts the size as needed. I know that the optimum would be to always manually choose from \big, \bigg, \Big, ... but for ... 
[brackets] [automation]
 

asked by Richard https://tex.stackexchange.com/landing/r/digest?cta=user&id=256917 Score of 2