Windows/Linux/Mac Eclipse plugin to compile and upload arduino sketches

Klaus
Not sure why you can't use Serial. All this works fine for me.
I assume you are referring to the console output that tells you that serial doesn't work. I ask because the eclipse indexer sometimes behaves weird and sees errors that are not errors.
As you already had plenty of problems it is -in my experience- best to just start from scratch with a new eclipse installation.
Best regards
Jantje