Wow, thats a lot of questions...
Fleet, 50/50 and frozen for 2 years.
Basically KA is no different to any other short haul airline where you work your usual 16 - 18 days per month with a mix of day trips, 2 & 3 day patterns and the odd 4 day pattern.
Delays, do your research, china makes up the lions share of the sectors so expect delays and therefor roster disruption.
Time to command, hard to say but if you have good experience and are truly a good operator then 12 months is not out of the question (could change though at any time)
Many have arrived in the past year or two thinking that a command will be handed to them in good time but have found the operation a little outside there reach.
Leave system works ok and there is a limited preferential bidding system that can get you either weekends off, early/late starts or max overnights. (chose one)
Part time????
You haven't asked about living expenses in HK so I presume you have done your research on that matter.
Hope this helps.
JY