The ink problem is WAY overrated, mine inked once a week for months, just run carbon. You dont even need to do a waterchange right afterwards.
And about the escaping, I would recommend using an eclipse hood, as they have the filter built into the hood and therefore can be COMPLETELY tight with only a simple mod (duct tape a 4" sheet of plastic over the cords outlet)
Feeding: Will need to be introduced on live foods, I used ghost shrimp and turbo snails. Within a week should be taking raw krill and silversides from the hand.
And about water quality, if the ammonia and nitrate arnt 0, and the nitrate above 10 the octopus WILL stop eating and die. They are VERY sensitive so be prepared to do a 10% waterchange ever other day and keep the sg a little on the high side.
Good luck!
Jon