What: Editing Cubase Audio events in WaveLab
How: By repairing a bug originated when the username has special characters, which is very common in many languages.
When: as mentioned in my email 13 Dec 2016, the WaveLab update 9.0.35 has solved the issue.
Who: A Steinberg employee called René, who payed attention to our comments and was very insightful. He fixed the bug in 24 hours although we had to wait a bit more for the results of the tester and update release.
Concerning your other questions, unfortunately, I can’t imagine how Cubase and WaveLab can exchange MIDI files. Have a look at the WaveLab 9 Operation Manual.