For some reason when I try to start Cassandra with this command:
bin/cassandra -f
The terminal gets stuck on:
Listening for thrift clients...
Is it normal? Does that mean that Thrift can talk too Thrift?
I am using Ubuntu Server.
That sounds normal. Cassandra -f doesn't create an interactive session, it just runs Cassandra in the foreground, but as a server process.
To interact with Cassandra, you can start a CLI session in another terminal window. See http://wiki.apache.org/cassandra/CassandraCli for details of how to do this, and the commands that you can run.
There are also clients for various programming languages - see http://wiki.apache.org/cassandra/ClientOptions
See also start cassandra with "./bin/cassandra -f", how to have back the terminal window?