As for the question of archival quality, Epson has been touting their long-lasting (100 years?) ink+paper combination for a few years now. I doubt I'll remember this discussion in 100 years, so I can't confirm it based on personal experience, but I assume someone would have cried foul if their claims were far off base. I doubt they'd stand up well to the pour-water-on-them test Derrick mentioned, though.

Getting the prints to fit properly was not a particular problem, once I figured out the separate steps of informing iPhoto (and later Photoshop) of the paper size I wanted (4x6 borderless, in page setup) as well as informing the printer of the paper size I wanted (full page, in the print dialog box). I do think the whole Print system in OS X has room for improvement, though.

One warning: At least in my experience so far, printing immediately to this printer tended to result in failures (printer unavailable/jobs on hold/whatever). I think the system starts spooling to the machine before the entire print job has been received from the application, then runs out of data and something chokes. I worked around this easily enough by printing on Hold and then releasing the job when it was fully spooled. Scheduled printing (i.e. print this 5 minutes from now) also works.