Cocoa/GNUStep compatible build

[pepijn de vos]

Hey,

I want to write a command line app in Objective C that needs to run on Linux 
and Mac. I read I can use Foundation on Linux using GNUStep.

Do I need the whole of GNUStep, or can I just depend on Foundation?

Can I use ARC, and is that recommended?

Why do I need to source GNUStep-make?

Should I use GNUStep-make on Mac too?

How? I'm using Homebrew, which does not have it. I read the Macports one, and 
it uses gnu-gnu-gnu. Does the mean I build against GNUStep on Mac too, instead 
of Cocoa?

Pepijn