I have a couple questions which I would like answered.

[Sexbad]

I believe you're speaking of the tech demo, not any beta. Big difference.

I'm pretty sure that the TD was built before they got a real writer to help create the story and help make the game's path logical, so it's not all able to be explained and has no real connection to any of the other games. It's similar because it takes place in mines and follows very similar styles of gameplay but it's not more than an outline of things to come, basically.

There's a section in the forum for the Tech Demo at the bottom of the index page. There's a whole bunch of information you might find neat in there.