Submit a multiple page PDF for print. 4 colour artwork and spot color on one page, Separate page for spot varnish. I would include the white in the file with the spot color. Everything set to overprint or knockout as required.
I have four Epson plotters 2-9880 and 2-9890. I have had service through Epson and they refer you to Decision One. The techs are great and very reasonable in there rates.
Heidelberg user for over 10 years, I have used many systems, Heidelberg SignaStation and Print ready are made for commercial printing. Support is the best in all aspects.
We were looking at the JPress and went with Indigo instead. Can you comment on your experience with the JPress? I like the direct method of applying the ink. No perfecting not good.