Is Northern Ireland still part of the UK?

Muslim migrants move there

Yes, it is. A simple google search would have told you this.

Yeap. Though maybe for not much longer if Scotland decides to break up the union. Or if Westminster finally realises that the North is more of a financial burden than financial gain. And then decides to consider letting the North go. 

British then, British now, British forever 

Yes, it is. A simple google search would have told you this. 

The rest of Ireland (6 counties) was to become Northern Ireland, which was still part of the United Kingdom although it had its own Parliament in Belfast. ... Ireland became a republic in 1949 and Northern Ireland remains part of the United Kingdom.

Yes, Northern Ireland is still part of the United Kingdom. 

Yes, it is.                          

Yes Northern Ireland is part of the UK, although the 'EU deal' means that Northern Ireland still has to live under many of the EU laws ( and UK laws too) to enable the border between ROI and NI to remain as they are now and means there are now custom requirements between Britain and NI..

Yes. Northern Ireland being part of the UK is a huge part of why Brexit has been such a nightmare to work out. Ireland remaining in the EU and Northern Ireland Brexiting from the EU is turning out to be a legal and logistical nightmare because there is no infrastructure to regulate the border they share.