There would be no integration. The greatest threat from an invasive species is virus, any contact would be very contained. We need only look to the post Columbian native inhabitants of the Americas to see the negative effect of uncontrolled integration.
Personally, I would want to learn from them, and teach them. But humanity, well, it'd probably be like District 9. And cal is right, but I think that we could work something out. They could stay at some type of moon-base and we'd wear hazmat suits when we went there and vice versa.
Very difficult. And how would they get here from wherever, if they= us? Think of all they would have to learn... all of everything we are, plus the other way around. THEN, socially, imagine TRYING to 'socially intgrate' with a Syrian( right now, they are in a civil war). And the difference between them and an ALIEN? District 9 is only one example.
I fight it tooth and nail with prayer. Aliens are fallen demonic angels and should have no part in our lives. (i.e. Noah's flood to rid the earth of the Nephilim) After watching a couple of movies my daughter wanted me to view I asked her, "What is wrong with humans falling in love with humans now a days?! It has to be some weird eyed alien or a zombie now!?"