Since init is the first process that runs, you can't use an interpreted language like ruby (since the interpreter would have to run first, which is impossible if your program itself is init). Maybe there's a Ruby-compiler out there somewhere, but as-is Ruby would be impossible.
This is simply not true. It's not impossible and it works exactly like any program would.
No it wouldn't. Either hack a quick shim to start the interpreter or rely on the operating system to figure out how to run a script. The #! is there for a reason.
> Since init is the first process that runs, you can't use an interpreted language like ruby