Berlin is a friendly city with a lot of foreigners from EU, Eastern Europe, Middle East, etc so you won't feel like a stranger here.
And I think that describes most startup ecosystems, just those also happen to be the conditions for really good companies to emerge too.
For me Berlin is a place where people can really be whoever they want, even two or three people in the same day. After all, everyone's an electronica DJ after hours ;)
If you're single an young, consider finding a "WG" - it's when several people live together in a big appartment with own rooms but shared kitchen. That's normally a student thing but that's quite cheap and can help integration. But that's also does not suit everybody.