Basing
If on a commuting contract, you will need to DH (ACM) out of one of their destination locations. In the USA, Seattle, Chicago, Boston, San Jose. if you live elsewhere, you will need to get your self to that location. Weather you consider it salary or not, $500 is for offsetting your travel related costs.
Either way, 11 days off means you will be traveling on your Off days, so Max in this case 9 days off. Keep in mind that you may be required to rest for a day after arriving in Beijing for work, I don't know if that is considered an Off or On day, I did't get that far in the process.
Keep in mind, Hainan said "not everything is perfect here, some things we are still working on, that's why we pay you so much money"
For me, I would still go, if I can get past the medical...