making changes to an award
 

Looking to book an award for ATH-IAD in August and IAD-XXX late this year or jan/feb 2012. I am trying to avoid cancelling an award because I don't want to deal with finding new flights from ATH-IAD and there are a couple good options to IAD now.

So If I book IAD-SJO as the second half of my award and then decide that I need to change it what are the options.

As I understand it I can only change up to 7 days before departure. So if I ticket ATH-IAD for 8/16 then I have to finalize my IAD-XXX trip by 8/9.

I will have to pay 20GBP to make the change?

I could change SJO to LAX, LAS or anything else is zone 3?

Changing to zone 4 would not be possible even though the miles cost is the same? For instance booking IAD-SJO and changing to IAD-EZE?