Earlier quoted context omitted.
If you want to change command key-centric menu shortcuts for a program, you can do that in the keyboard pane of system prefs.
No. In Linux I have global keyboard shortcuts to launch specific applications and do some other stuff. I hit a key combo and a new terminal pops up, or a new tab pops up in my browser, or a new email, or the Python shell, or whatever else I want. It launches regardless of what other application I'm currently using. In OSX, last time I looked (maybe a version or two ago), there was really no builtin way to achieve the…
It's not quite as straightforward, but you can define custom services using Automator, and subsequently bind them to any key combo using System Preferences.
Since Automator workflows can do pretty much anything (like running AppleScripts, shell scripts, manipulating other apps etc...) you're pretty much free to do what you want.