I have a question about the shielded address.

1) Can I send coins from a B Address (Transparent) to a Z Address (Private)?
2) Will it work with a Electrum wallet or do I need the full-node
3) If I send it back to a B Address would the block-chain trail be blank or would it pick up were the coins previously left off?

I asking because I want to move my Transparent coins off the grid but also don't want to come back and haunt me later if you know what I mean. Like once the coins get moved into a private address no can see them or know how many there are, but if they ever end up back on a B address would it be traceable back to the original B address it was mined to?