Sulla, when he came back from the East, came by ship and marched north up the Italian peninsula from Brundisium (modern Brindisi). Caesar was coming from the NW. Pompey retreated to Brundisium and his legions took ship there for the East. So Caesar's march was exactly the opposite directionwise of Sulla's.

About the Rubicon, here is something I wrote in a previous post:

The Rubicon wasn't a boundary within which soldiers weren't allowed. The Rubicon first occurs as a boundary for Marc Antony, who was forbidden from taking an army from Italy north of the Rubicon. Anything associating the Rubicon with the line beyond which it was not possible for Caesar to withdraw occurs only after Lucan's epic poem on the civil war, written at the end of the Julio-Claudian period. Even the pomperium, the line around the city separating the military world from the civil world, could be crossed in certain circumstances, like the public violence in 53/52, in which Pompey had to occupy the city to allow public business. That's not to say Lucan was wrong about Caesar crossing the Rubicon, exactly. I find it hard to believe the Rubicon suddenly became important for containing Marc Antony, but meant nothing to Caesar five years earlier. Neither Caesar nor Cicero mention it though, and it certainly wasn't a limit on having troops since Pompey had two legions preparing for his Parthian expedition inside the peninsula.