Questions about cross platform purchase

[tekdemo]

I'm really excited to play this, but I'm a cross platform user. I use Linux as my primary desktop OS, and I'm really excited to have proper Linux games like Minecraft and Amnesia that I can play without rebooting to Windows, which I reserve solely for games.

That said, here's my specifc questions and issues:

• I tried running the Linux demo, which gave an error of : [Unexpected ) on line 136: Expecting "then"]. This kinda dashes some hope that the game will run flawlessly on my system*.
  
• If I buy the Linux version, will I still be able to install and update the Windows versions?
  
• Steam is amazing, and having a sale. I really like having the automatic update, and ease of re-installs, as I hate keeping track of CD keys.
  
• Is there any way of downloading and installing a Linux version after making a Steam purchase?
  

I tried finding the solutions to this, but I couldn't find what download/activation/rights management was enacted, nor if it was account based like Blizzard or Steam.

Anyway, thanks so much for making a Linux game, and I hope you keep supporting us in the future. It means a lot to us free software advocates.

*system: Phenom 2 X4 @3.4Ghz, Nvidia 8800GTS, Asus M4A79XTD-EVO, running Kubuntu 10.10 64 bit (Kubuntu is a Ubuntu derivitive, using KDE instead of Gnome)