I don‘t have al the answers, but I do know that commuting is difficult/near impossible as they have a random roster. If you are planning to fly parttime it may be possible.
From the start you can buy standby tickets for Eurowings flights (EW Europe and EW Deutschland, and maybe even EW Discover)
After 6 months you can buy stafftickets for LH, LH group airlines and many others.
EW threats it’s staff fair, but rumour has it that the pay in PMI and PRG is poor. I haven’t seen the pay for ARN but I don’t expect it to be much better.