I took this flight last week!

Boarding in FRA was via a coaching gate. I was in C and was able to take two bags - both a laptop bag and an overnight bag. My overnight bag was taken at the aircraft and returned planeside in Ljubljana (as you would see in a US regional jet flight). The gate agents didn't seem to be forcing passengers in Y to check in second bags.

Adria is a full-service airline. In C you get a meal and drinks on a 1hr flight, and I believe passengers in Y get drinks and a snack.

Ljubljana airport is tiny, so it's very quick to get through. It's a 20-30 minute taxi ride from downtown Ljubljana.