Questions about best practices and specific settings (express mode)

Hello all! I'm trying to understand some Stellar options but I am coming up short as the official ALE stellar manual is not very specific on use case scenarios. Hopefully, these are easy questions for the more experienced people around here. Here goes:

1 - When creating a new WLAN, two of the options there are "Multicast" and "Broadcast ARP". They are OFF by default. What are the scenarios where I need to turn either or both of them ON? What type of problems and symptoms are associated with these options?

2 - DTIM option should usually be set to 1. I've gathered that much from my online research. Any symptoms and scenarios where I need to change it around to different values?

3 - Same for the client rate and management rate for both 2.4 and 5GHz, in what cases do I need to play around with these for best performances?

4 - Moving out of the WLAN options and into RF options: I usually change the global 5G width from 20 to 40 to allow for more bandwidth between wireless clients. Is this a mistake?

5 - Still within RF, the Short GI option: I understand we should turn if OFF if the APs are in a very metallic environment. Is this correct? What else should I know about this option?

6 - Lastly in the access, more specifically the black and whitelist section, I'm curious about the Multicast whitelist. Every now and then I have issues with AirPlay and I wonder if I could play around with this to try and sort it. Any examples of how I can use this to my advantage?

Thanks for your time guys. I'm just trying to learn as much as I can :)

Hi, Please find the answers as attached to the knowledge I have.