>>1
Take the official GNU Emacs tour: https://www.gnu.org/software/emacs/tour/index.html
You should use evil-mode or Doom Emacs if you want vim keybindings. If GNU Emacs is too slow for you, run it as daemon and enable native compilation (JIT compilation for elisp).
Will I be missing anything if I continue using vim?
* magit: https://magit.vc
* org-mode, it's really versatile: you can use it for notes, agenda and even spreadsheets! https://orgmode.org/features.html
* dired: https://www.emacswiki.org/emacs/DiredMode
* GDB GUI: https://www.gnu.org/software/emacs/manual/html_node/emacs/Debuggers.html
* SLY or SLIME (for common lisp) and Geiser (for scheme).
* M-x regex-builder
* M-x man, read man-pages with hyperlinks!
* Many fun amusements: https://www.gnu.org/software/emacs/manual/html_node/emacs/Amusements.html
* elisp, the superior language for writing extensions (Lua in NeoVim is also decent but VimScript is bad). I think you need to restart (Neo)Vim when you change your config file, but on Emacs you can just run M-x eval-buffer. Emacs also has easy customization using M-x customize etc.
Also, I think Vim has recordable keyboard macros, too? (if not, you are missing an important feature!)