KevF, I have not looked at this part of their website but I have bought tickets directly from them. From memory if you pay close attention their is a section detailing the cost to change a flight or to cancel and refund (if allowed).

Ctrip will give you very good service in English if you run into this. May be worthwhile for you to look at booking with them. Air China is fine, too, but their English language support is not as consistently good as Ctrip.

As for your last question, I have never seen a ticket where you could change the destination. Only refund and repurchase.