Hello,
I work for AL since 2009, regarding the screening I don't remember a lot. On day one, the most important part is the dinner, some applicants believe that it is not part of the assessment, but that is not true! If you have in the next morning your sim at six or seven o'clock, I would recommend you not to stay until midnight and drink the whole evening. Most candidates think that the dinner is not part of the whole process, but have in mind that these hours during dinner give the recruitment team an idea who you really are!
The sim is pretty straight forward, you fly approximately 45-60 minutes in a 737CL or NG, depending which sim is available. As far as I remember, the expectations for persons with an 737 Rating are higher, but the programm is still the same. You'll make an raw data takeoff without A/T and climb on runway heading to e.g. 5000ft, there after some airwork followed by a NDB Approach and a single engine ILS Approach, it's not really complicated. If you pass, you will go straight to your interview, where you spend another hour. That's it.
If your German is good enough, I wouldn't be worried too much about it. But yes, the whole screening is in german, if you have any questions do not hesitate to ask. They will help you.
Regarding the salary, I really hope that your expectations are not too high. We have lost plenty of SFOs to Norwegian, but you can negotiate because they need people. We get two more airplanes, one is coming in July and one in September, I heard that there is a third unit in the pipeline! They lowered the requirements to upgrade all the FOs to captains. It's just a rumor, but they might have to take DEC because we don't have any experienced pilots in the right seat, so maybe you are in a better position.
Good luck