I think I'll be using Star rather than OW as it looks like the rules are less messy (little concept of alway travelling in the same direction).

Can I just check that members think that the following routing would be within the rules:

Miami -> Buenos Aires
Ground transfer
Quito (Ecquador) -> Los Angeles
Los Angeles -> New York
New York -> London etc etc

My concern is that I fly back across the UK from LAX to JFK. Is this OK?

I will be flying first class. Does this mean I get charged for each change of date/destination? I ask because my plans after the first few hops are quite fluid and I am likely to change a lot of the destinations and dates in one go - so would that just be one charge?