I have a red coris wrasse and he is usually pretty good with inverts, hes getting pretty big now though and i noticed he will bite at the odd invert, like our snails and abalone, he is also starting to show his fangs more often. Also all of the little star fish disappeared since we added him. Can't keep any shrimp with him either. Guess he's really not that great with inverts then hey haha, hes okay with larger inverts i guess like crabs.
Midas blennys can be jumpers but all fish can be. Once they are established they are unlikely to jump. I'd recommend putting a temporary lid on the tank until the midas blenny has found a hole in the rock that he likes.