I want to fly routes from mainland China to and from HK/Macau, but I don’t know if it will count as international or domestic. Also, can I fly a route from HK to not China and back if my HQ is in the mainland?
In AS, both cities are treated as seperate countries. Hence you cannot fly passengers from either Hong Kong nor Macao to other destinations than China.
You will have enough traffic flying from HK to mainland anyways. Even as a Chinese carrier you can build a large base in HK just flying to mainland (2000 departures+). It would be sweet to be able to fly long haul from HK but you have so many large Chinese cities in the area anyways to fly LH from. Flying LH from HK would just cannibalize your other hubs. Plus that there are so many cargo carriers stealing your slots in HK making it hard to build a hub there.
In my experience China has almost unlimited demand (as long as you find slots and build hubs) that it is way easier to fill planes in China than EU and US.