First six months: only travel to your home port is allowed (you will designate one on the 2nd interview I believe).
After that: you can buy ID90s anywhere CX/OneWorld flies.
After 1 year: you can buy ID90s on everybody else.
ID90s is expensive buddy! Cathay charges for the ever increasing "fuel surcharge" to staff as well as the passenger. This tax plus airport taxes will almost double the price of the discounted ticket that Cathay sells you.
To put things in perspective; you will be about 500USD poorer if you were to buy a ZED/ID90 to go from Hong Kong to Vancouver and Back on Bidnid class.
There is "jumpeating" on Cathay only. But this is not free, you will still be charged with the ID90, all it means is you may occupy the jumpseat if the flight is full. You'll get to where you want to go, but it is a worse deal since you're still out 500 bucks US only you get to sit on a Flight Attendant jumpseat for 14 hours (YVR-HKG for example).
You can only print out these ID90 tickets in Hong Kong. So if you're in Vancouver skiing and lost your belongings and tickets stolen, you are out of luck! However, with that in mind you are allowed to print as many as you want and they are good for 6 months. You won't be charged until the ticket is used.
You must have ID90s for Business class to be able to sit in Business Class (costs more). Cathay will not allow any employees to upgrade for free. I have been on flights where there are over 40 open seats in Business and I had to ride in Economy. Cathay is not your average N. American carrier where employees look out for each other. (They can't, 'cause they'll be canned if they did)
When I went to the 2nd interview I asked the lady at check in 3 questions and they went like this:
Can I be upgraded: "no"
Can I get an emergency exit seat: "no"
Can I get a aisle seat: "no"
Expect some of the same treatment when you staff travel on CX as employee.
As a Second Officer, I believe you will be "level c" employee? (correct me if I'm wrong) Therefore you are NOT ALLOWED to ride First Class. Only people after 7 years with the company or managers can. Yes, they like to put you down. Yikes!!