1. Yes, the mummy has been engulfed.
2. 'ichor actually lasts nine plies' ---- hmmm.
This relates to the specific case where a piece is compelled to move off.
The ichor certainly lasts ten plies, so in this situation the ichor must
have been created during your opponent's move. My thought was that since it
will finish its evaporation at the end of your move, you can effectively
satisfy the compulsion to move off by simply staying where you are; and at
the end of your move the result is that you are no longer standing on icky
ichor.