Hi,
1) Yes, even in version 6.5 it can do that, via project variants. One can have mobile and HTML project variants within the same project and same content, just different look and feel.
2) I assume you mean Web 2.0 features that are empowered by the product, not within the content editing area. Well, all existing web 2.0 works with the product. Facebook and twitter sync, flikr galleries and more. Actually, they work even with version 6.5.
3) Relatively painless, please search this forum is upgrade gotchas to watch out for.