Hello, my name is Syd and I am with Epson America
This is an excellect question as use is taken into consideration before purchase. With any inkjet printer, sitting idle for weeks or months at a time can give a nozzle clog. Built into Epson printers is a timer that knows when the last time it printed. If it has been a long period of time (weeks), the printer will do a very heavy cleaning automatically before printing. This is normally done by the printer and no intervention from you is needed. This is why it may take time while the printer light is blinking and the printer to start moving.
For pigment vs dye, the result should be aprox the same. The printheads are sealed closed by a rubber 'cap' when the printer is not moving and with both a cleaning may not even be needed.
For the ink cartridges, you would always want to keep them installed in the printer at all times as this is part of the seal. While there is an expiration date on the ink cartridges, this is to guarantee exact color and does not affect clogged nozzles.
If you have other questions with this or other issues, please feel free to contact 1-800-GO-EPSON and a rep can assist or help explain better.