Make this your landmark. Buy a 3 day unlimited ride pass (bus, metro, train, tram) for 16.50€ is better than the Roma Pass. Go to Conad for groceries (Masala entrance).
Leave plenty of time to find your bus as it's disorganised. Note that Terravision asks you to check in at their TerraCaffe (inside the station by platform 1) even if you have printed tickets with you.
Se dovete prendere il 90 express andate alla corsia in fondo ( vicino l'entrata metro) Anche se non c'è alcuna indicazione del 90 fa capolinea lì ;) P.S. Se non sbaglio nella corsia c'è scritto 176 ;)