First post (been perusing this website for months and the lot of you are currently my favourite people in my life) and have finally today booked my DONE4 (It's currently on hold with AA), but I did have two questions which I hadn't seemed to be able to find an answer to specifically.

The first: if, due to a seat being unavailable, I'm booked into Economy on a DONE rtw, but later on a D or W seat becomes available or I change my date, is switching possible with ease? Would that be a free "date/time/oneworld carrier/inventory" change? Or would that change cost the US125?

Secondly: With E-tickets, open-dated segments aren't possible anymore, is that correct? So for example if I choose to include a "Surface Segment" and a Oneworld airline runs that route, is changing that "Surface Segment" to a flight later when it's available considered a "Re-route" even though the ticketing points remain the same? I would argue that the route was running but seats weren't available at time of booking, but I'm not one to persuasively argue any point, so...

That specific flight is UIO-SCL. Instead of booking it as UIO-MIA-SCL, which would add another continent, I told the RTW operator to leave it unbooked - it's not present on the reservation page.

Thank you.