I flew Air Dolomiti MUC-BLQ in May. I seem to remember it being a new, clean plane (ERJ 190 I think). No problems with service, that I recall. As far as carry-ons, be aware that RJs have smaller overheads, and that European airports are sometimes more strict about carry-on policies. We boarded via stairs so it's harder to hide an oversized carry-on out in the open.

This was a Lufthansa coded flight booked directly with LH and I think they pre-assigned a seat, but I don't remember for sure. It should be analagous to flying UX here, so you can probably change your seat on the website.