The borders are all easy, with short waits, clear and consistent document flow, no bribes (don't ever offer a bribe to anyone in Chile unless you're very confident you know what you're doing). I've never heard of anyone needing an international license on that border, although I always carry one against the eventual, inevitable need. But you need to confirm that you can take rental bikes across the border if you haven't already done so.
I took that ferry. It was fine, except it was late leaving, later arriving, and couldn't unload vehicles (including bikes) for 6 or 8 hours due to "tides." I've heard that's not unusual, so don't schedule too tightly.
The southern Andes get increasingly gorgeous the farther south you go. Where you're heading you'll see some of the less-remarkable areas if you like mountain scenery--mostly pleasant, pretty, interesting and fun, but not truly spectacular. The Andes also get increasingly gorgeous if you head north to the altiplano, but with a totally different feeling to them.
Hope that's helpful.