(But to be fair even a minimal Emacs is about 20MB RSS these days).
Back then mine was the "scary" machine in the workshop with its AMD Duron 700 and a whopping 512MB of RAM... and Emacs was just about usable on it!
He knew what he was doing.
From the documentation. I don't know why they didn't make it the same, but this is how it is, though maybe because M-butterfly is rather hard to press.
No, there aren't.
Have you tried literally every other text editor?
I switched from Vim. In Emacs, I can inline previews of LaTeX formulas in the same buffer as the one that I am editing. This is possible because Emacs has a GUI. Vim cannot do this because it runs in the terminal, and it also doesn’t seem possible to do this in gVim.
Meanwhile Emacs implements Vim’s modal editing through evil mode. So for this use case, Emacs seems to be strictly better than Vim.