Riding through North Greece

I am Sonya Dimitrova!
Few Bulgarian Cyclists and me are going to North Greece by train to Seres on 1-st May. Then Planing to ride Seres - Drama - Kavala - (ferry) - Tassos - Potos.
Any kind of info about the roads (we prefer to avoid the main roads), about the way to care our bikes into the train or ferry, or any info you think will be important to know are welcome!
Appreciate your support! Thanks a lot in advance!
Greetings!