Hey!

Well, after some delay, here are the answers.

1) No EY miles from any of the flights. Perhaps LH would credit MM miles but I am not interested in those. Also, no tier segment! Apparently EY tier segment you get if and only if your flight is sold as EY and operated by Etihad (except maybe Air Serbia and Alitalia).
2) 1 piece only, was not allowed 2nd bag (I had it ready but didn't really need it that much so I didn't push)
3) Not possible.

BTW, EY found a new level of incompetence. On the return flight I had AUH-ZRH-PRG, sold as LX and operated first by Etihad and then Swiss. Upon check-in at AUH (and this was First Class check-in) staff told me that the ticket is only to ZRH and that I must have bought the tickets separately and it is my responsibility to pick up the baggage from the belt and check-in again. The scheduled layover was ... 45 minutes! It took close to an hour for them to finally override the system and send the bag to PRG directly. Needless to say, I missed the connection in at ZRH because it is not doable in 45 minutes. Horrible experience with rebooking on a later flight and, of course, no compensation under EU law. I wonder if EY can get any worse?
[MENTION=886412]ohitsascythe[/MENTION] I would book LH due to the price.