Moved to Ireland in October 2016. Filing tax returns in two countries??

Dear Community,

I hope you can advise me a little bit on some tax questions. I already researched intensively on the internet, but most things are still very unclear to me. I appreciate every comment and every reply, I unfortunately can’t afford any tax advisory so I must struggle through it on my own.

My situation: 

- Moved to Ireland for a regular job on October 1st, 2016. Before that, I only lived in Germany. (<183 days in in Ireland in 2016 -> no tax resident in Ireland, also didn’t elect to be one).

- Before I moved to Ireland, I made 4530€ gross income in Germany (over 4 months). In the 3 months I worked In Ireland, I made a gross income of 7388€. In Germany, they regularly deducted income tax from my pay slip as well as social insurance. In Ireland they didn’t, I only paid PRSI. I’m PAYE employee.

- Only have a bank account (DKB) in Germany and always transferred my salary to that account. Also have some very minor interests and received a dividend of 10€ in 2016 (don’t exceed the “Sparer-Pauschbetrag” by far, a Tax exemption for capital gains in Germany).
 
1. Most important as the deadline is very close (30th of April!!): Do I have to declare my foreign incomes and assets with Irish Revenue? So, telling them about the two German bank accounts, the assets and the interests? As well as my German income? For 2016, although I was no tax resident?

2. Where do I have to file tax returns? In both countries? But I guess I might only have to pay income tax in Germany as I was tax resident there in 2016 (due to double taxation agreement)?

3. In case I also must file a return for Irish taxes: Do I use the Form 12 via Revenue My Account?

Hope you can help me further and point out if I forgot something so far.