I've bought a Macbook today and I was wondering what the best way to use Linux software is? Obviously there are bundles of considerations involved like library usage and package management.

Is there a package management solution and if there is does it merely blindly recompile the Linux options or does it use things like the Mac Qt and GTK ports where they are available?

Mac has a frame work called Cocoa and Carbon. You can write applications using that framework. You must user Obj C or Java. Mac has Qt which can be downloaded from Qt website.

I think there are two (maybe 3?) working package managers that allow for Linux software installation on OS X machines.

Fink is probably the best known, Darwin Ports, and MacPorts, and I recall there was a Gentoo portage manager in the works a few years back...

I have used a couple of them in the past, but have not enough info about their current status to point you to one over the other, or their current strengths and weaknesses.

In most cases, if you find you do not like them, they are pretty easy to remove... You'll need to do some digging and fiddling to determine which will suit you best.