Believe it or not, Asphalt 5 HD is in the market, and the demo does take you there. The annoying thing about it, is that if you do purchase it, Asphalt 5 and Asphalt 5 HD are two different games, and the demo will sit along side the "full" HD version you're directed to purchase.
Can't say why there is a difference in prices listed, except that maybe the price went down or up, and the 6.99 is hard coded in the demos screens?
Yeah... Someone posting paid software for free. Isn't that against the TOS here (looks like they were removed already), as well as raising massive red flags? Gameloft uses DRM in their apps, so at the very least if they did install, they were tampered with. Worst case, they were acting as trojan horses...