Same as anywhere else in the world (at least where people can be made to pay the price of a medium lunch for an insane amount of sugar and caffeine): Starbucks.
Yes. DB, the German railway company, offers Wifi hotspot service at selected important stations which allow free surfing for 30 minutes. According to their page (in German; cannot find an English version), over 125 stations (listed there) offer the facilities; among them Munich central and Donnersbergerbrücke, Frankfurt central and Hauptwache and both cities’ airport stations.
To connect, just connect to the network Telekom. Open your browser with a random URL. Click Online gehen to connect; as soon as you can see the timer running down, you’re good to go.
In my experience, while the Wifi isn’t the fastest it is certainly useable.
Credit:stackoverflow.com‘