Hey guppy,
not sure about the time-off flying. There is a weight limit and I think a restriction on flying commercially...has to be considered in total hours flown. I don't remember it being restrictive though.
I am like you in that I have kids in 1 country, job in another...admittedly oz vs US. I have commuted and I have been based. There are pros/cons to both. If you are an 'every 2nd weekend' dad you will greatly exceed that. If you want to coach the football/basketball team your kid is in, get a different career!
If you want the job with CX, sell yourself as being very HKG centric. I can tell you that SOs get lots of time off. -400 pilots get a lot of time off...in fact I have had friends spend TOO much time off in australia...over 183 nights per year(a local tax threshold thing!). So unless you want your kids 50% of the time(in which case give up flying) I don't see CX as being a major impediment. I have gone 6 weeks without seeing my kids but I have averaged over 1 in 3 nights with them over the last few years...and like you they are an extra flight away from an online port.
So if you want the job, you can make the kids thing work. Just bear in mind that from month to month, and year to year you may go from 'feast' to 'famine' and vice verca for time off and seeing the kids.
Hope this helps
another DD(divorced dad)