Eres paciente pero divertido
"Eres" already implies the person it's talking to (you, in this case), if we wanted to make it formal, we would've used "Usted es" (You (formal) are)
The answer is (acabe) because it refers to the fact that he has not finished his studies and when he finishes it he could finally be an astronaut.
Hay sillas delante de los ordenadores.
