1) I wouldn't pay $200 more to fly CX. CX has some strengths, but given cost is your biggest concern, it is not really worth the $200 ($200 is close a 20% premium!). I personally really hate the non-recline economy seats on long-hauls as it is very difficult to sleep in (it is great for sitting so short flights are fine)

2) Try some of the travel agents near school campuses that have access to student fares. Couldn't hurt to try.

3) $1300 for CX sounds about right

4) I've found CX online to be quite good relative to travel agents, but if cost is your major concern, wouldn't hurt to price shop a little

5) Does CX price match? Not that I know of.

6) CX fares go up quite a bit when you want >6 month validity. When booking online you can select a higher fare class and you will the ticket validity in the confirmation page

7) As many have mentioned, it's very easy to go to HK from the airport. The train takes 25 minutes to central. Many nationalities can enter as a tourist without a visa.