I think you mean "downgrading". The Premier is not an upgrade, especially for someone in your situation.
Yes, but not with an un-modified TiVo. It would have to be modified. Once done correctly, it can transfer to a PC. It cannot transfer directly to a Premier.
For more details, see the "other" TiVo forum.
It's more than just that, although the programs are indeed encrypted. They also reside on a file system your PC cannot read (or write).