The idea may be open to votes but it was rejected from the start.
This offers an explanation why it's not going to be considered regardless of how many people want it because it is logical to have the main menu bar at the top.
I've had several people asking for this in the Thunderbird Support forum. In the end I created my own question and answer so I do not need to keep retyping the required info.
The file menu belongs to the upper left position of any window. Nothing above it. Please, please, please don't break well established standards for whatever reasons.
re :Would also like to be able to add color to some of icons on the menu bar with quick identification.
You would have to use a personal customisation via userChrome.css which has always been the case for anything of this nature. However, this particular request for a new idea is not the same as the title of this topic, so you would need to ask as a separate Idea.