Look into Spacemacs - it addresses a lot of what you want. It understands file extensions and automatically downloads curated sets of packages for what you're

Look into Spacemacs - it addresses a lot of what you want. It understands file extensions and automatically downloads curated sets of packages for what you're editing (no more arcane copying and pasting) The key bindings are set up so that pressing the first part of a key chord brings up all the things the next part of the key chord could be in the mini buffer