American Dreamcasts have a grey piece of plastic over the orange light. Japanese Dreamcasts have a clear piece of plastic. American and Japanese dreamcasts will only play games from their own regions unless modified.
The aftermarket for Dreamcast games is not significant, especially when compared to Sega's previous console, the Saturn. Most Dreamcast games were produced in sufficient quantity to not be considered rare, although a few Japanese titles can run you up to $1000.
There are no dreamcast emulators that will run dreamcast ROMs. The dreamcast is cd-based, so you can either download an emulator like Chankast, and use actual dreamcast CDs (you can get them for a couple of dollars/pounds) or download dreamcast ISOs
Yes Sega still makes games but not necessarily for DreamCast. The leaders at Sega realized that they can't compete with the other major players in the console market. So they switched to making games and phased out the console for the Dreamcast. The games they create are made primarily for the other game consoles. The Japanese market may still be open to game production for Segas Dreamcast.
The Dreamcast cannot emulate itself, however, it is possible to obtain a Dreamcast emulator for a PC. Various emulators, such as Chankast Alpha, exist.
No a Dreamcast game will not play on your computer but just putting the disc in there. You would have to play a dreamcast game on a dreamcast system.
Dreamcast Collection happened in 360.
Dreamcast BIOS dumps are not legally redistributable. You must dump them yourself from your own Dreamcast.
Dreamcast Collection was created on 2011-02-22.
They can only play games that are designated for the dreamcast.
You only play Dreamcast games like Sonic Adventure on your Sega Dreamcast instead of Sega Saturn.
They stopped making Dreamcast Consoles in 2003.