"Do they allow Pilot crew members to jump seat on their days off?"
No jumpseating what so ever, there are some employee zone fares available on Lufthansa.
"What to expect if offered a interview?"
The first day is a basically a psych and computer based testing day. I've heard Lufthansa uses similar testing. There is about a 30% failure rate that day and you are notified that evening in your room if you need to go home. You can prepare to an extent but if you're a nut job, I'd think twice about wasting your time going. The Dr. is very sharp.
Then you have a sim check in a 737 NG. It's straight forward. steep turn, VOR approach, V1 cut to ILS, visual approach. You can use the A/P for most of it.
There is a "one on one" interview with some technical questions. It's fairly standard and no trick questions. It's mainly to get an idea of your personality.
The medical is usually the last thing you will do and it's pretty intense. If your in poor shape, high anything. Get it taken care of, if possible, before you go in.
It's a hard process and then once you make it through, the training lasts about 3 to 4 months and that is stress free. They want you to make it through and are very helpful.
Of the Chinese airlines, I'd say Jade is probably the best and that mainly has to do with the fact that there is a lot of foreign management and most of the pilots are expats. They are losing guys of course as the available jobs throughout the world are starting to increase. Jade has announced that there will be upgrades which is welcome news for the guys.
Good luck and if you didn't make it to the sept interviews, I'm thinking there will be more to come.....