I disagree on the four color process, because on anything but white, you are going to have a white base with translucent inks on top (CMYK inks are translucent). Simulated process is the way to go...and to be reasonable in price you are going to order over 144.
7 colors is a standard for an 8 color press (one station will be flash) and to truly get a wide gamut, you will need a 12+ color machine, with 2 flashes in. Simulated process standard had 9 colors for separations (software default). However, I use photoshop to make my own as I have found that 80% of the time spent in with the simu process software tweaking colors. Just easier in photoshop for me.
BTW - to truly get great prints requires a dedicated shop with a lot of high end screen systems, outstanding prepress dept etc...all to capture the dot, print the dot and blend the dots for a wide range of color...things we do at Legends everyday!
hope this clarifies somewhat