Welcome to my hometown!
If you're looking for a metal bar afterwards, go for "Paule's Metal Eck" in Simon-Dach street. Map: go to Google maps and type in the following: Krossener Straße 15, Friedrichshain 10245 Berlin, Berlin, Berlin
From Alexanderplatz, you should take the U5 (underground), direction to Honow and jump out at Franfurter Tor (like 4 stops). From there it's a ten minute walk through one of the hippest districts in the world.
Even if you don't like the bar, there are like 100 others in the Simon-Dach street. You'll love it!
Have fun, see you,
J