This is really a matter that you should look up yourself.
Relavent links to their pages (mostly in English) have been listed below.
It is only there that you will find the latest information available.
The relevant point in the FAQ page seems to be:
I have an appointment to collect my electronic residency permit (eAT). Can I still come for this ...
Under the EU blue card scheme you are allowed to leave the country for a temporary absence of less than 12 months without affecting the blue card validity of the blue card, and hence can return and continue at any stage.
During this period however you would be expected to continue to keep your primary residency in Germany which means:
Continue to pay ...
What do we need to submit for a visa application for residency in Germany?
None. As EU citizens, you cannot get German visas. As noted in the other answer, you have to register when you move there, but the only document you need is a Croatian passport or ID card. This is explicit in the free movement directive, 2004/38/EC. Article 6(1):
As European Union citizens, you do not require a residence permit to live in another European Union country.
Some countries (like Poland) require you to apply for a residence certificate after taking up residence.
Germany does not, but you are required to register at the local registration office (Meldebehörde) in the same way as a German citizen must.
Yes, after a 2 year employment (without a time limit), you can change your employer without prior approval.
Note: Your residence permit for the purpose of employment/your EU Blue Card does not have to be amended, if you
have already worked for at least two years with a residence permit for the purpose of employment or
you have resided ...
Lucky you added midi to your question.
It allows a regulated input of fresh air without having to open a window.
The previous renter probably left it there.
See product information (in English) below.
AEROMAT midi - Clever passive ventilator with flow control
Assumption: With Kreisverwaltungsreferat I assume you mean the local registration office, which in different areas, has different names.
The local registration office is where you report your changed status, but you must also apply for the change of the tax class at the tax office (Finanzamt).
The link below offers a PDF Application form for this purpose. ...