I posted this on milepoint, but as this is my first ever miles redemption, I thought I would get more advice. And yes, I know I'm starting this late, but I have been so busy that I only just now decided to use up my BA miles while I can in South America while the going is still good.

Basically, can anyone let me know if this itinerary looks ok at first glance? All flights show as available on BA's website, so I assume they are really available (and I'll just have to call to book - $20 fee is fine).

NYC-LIM(stop)-IPC(stop)-SCL(destination, stop))-MDZ-AEP(stop)/EZE-NYC, mid-May

I assume AEP and EZE count as co-terminal airports - I'm routing through MDZ to avoid a reciprocity fee. Will I encounter any others?

Two of us are going, but I only have the 100K BA miles, so it'll be in economy, alas. I wish it were in biz. 80K total, by my understanding.

Two other questions:
1) Do date changes cost anything if I need to make them? I'm getting conflicting results from a search on whether that counts as a refund and rebook or a fee-less change if the same number of miles are needed.
2) When is the absolute last date for booking these under the old system?

Thanks!