Understanding how Native Instruments Traktor analyzes and beat-grids songs

Question

Quick Summary: How does NI Traktor determine:

• BPM (beats per minute)
• beat-grid
• key of song
• auto-gain

Detailed Description: I am very interested in understanding exactly how Traktor analyzes a song; specifically, I want to know how it guesses at BPM and how it determines where it will set the beat-grid. I would like to figure this out for a couple reasons, but the biggest one is that I am investigating the possibility of writing a 3rd-party software tool to beat-grid and set BPM of songs for Traktor. Traktor is an incredible DVS (Digital Vinyl System), but beat-gridding tracks within Traktor SUCKS. Having worked with audio files on all kinds of hardware samplers and in many different PC and MAC audio file editors, I have a great idea of what GUI design would work best. And, if I can do a software program to beat-grid songs for Traktor, I'd really like to do an IOS port so that I can grab my iPad and prep songs for Traktor wherever I am.

I am most interested in the way Traktor determines the BPM and beat-grid: if anyone can point me at open-source tools that do this/similar tasks, please let me know.