Questions about moving to Denmark/Århus

I'm going to move to (probably) Århus beginning of January, and I got a few question specifically about the city and live in Denmark in general. If there is a better community for stuff like this let me know!

Live in Denmark

• I probably have my apartment secured but are there general things to look out for?
• Are there any must-have-apps for daily live? I already found the DSB app, rejskort and rejsplanen app, but is there for example something for national/local alerts (Germany and Finland have that for example).
• I already have one specific question: why does DSB offer both to check in and out for a trip and tickets for a specific route?
• Any other things I might not be aware of? I already lived other Scandinavian countries, so I don't expect much if a culture shock.

Live in Århus

• I'll be trying to join a pen&paper group. Any advice where to go looking?
• Any areas to avoid?
• Any hidden gems? Might be a favorite café, bar, beach etc.
• Any other useful things?