Hi and welcome. I'm going to try my best to help, but I have no basis in my information except for what I'm reading and find on websites, so... use information at your own risk.
This is Croatia to/from Italy (ferry). Not sure exactly what your question is...
Ferry site 1
another site on Croatia/Italy.
Again, haven't been to Greece yet, so I cannot vouch on behalf of any transport system.
Here's a link
to a website for some transportation.
the main site for tourism in Greece. I'm sure they'll have lots of great links.
Remember if the site isn't in English, to look around for a US/Brit/Can flag
Hope this helps a little.