> How seamlessly can I run 68k games? I heard games that need > a video card won't run properly
It's the other way round. m68k games that can use a graphics card have a good chance to run directly on MorphOS. It's the games depending on the presence of the Amiga chipset (OCS, ECS or AGA) that won't run directly.
> How well can it handle modern website like Youtube and Facebook?
I don't know about Facebook, but Youtube works well with merely watching videos. However, there seem to be problems with logging in to Youtube (and other Google services).
> What kind of websites are limited?
Anything depending on Flash, Java or Silverlight technology. Furthermore, websites which strictly demand a very recent SSL/TLS implementation.