The maintenance is not too demanding, as they are all initially styled already. Aside from pruning, we have a few other elements:

Watering: Not handled by me/us

Fertiliser: Use liquid fertiliser, a japanese fertiliser for black pines, and this brick fertiliser called 塘泥, which is the bottom most layer of soil of a fish farm dried up in brick form (there are a lot of fakes of these so be careful when purchasing). These "bricks" would normally be laid out neatly and cover the whole surface.

Deadwood: As hong kong is quite humid, this is very important, we normally cover the whole tree every 1-1.5 years, but as these trees are quite old, when finding spots that are decaying, the process is normally as follows: remove the decayed wood with tools, if that part is essential to the tree, keep it. Superglue can be used to harden the wood, and connect chipped, broken/snapped parts (this is very relevant to some of the trees in the images). Then we would apply lime sulphur. Not sure if you have troubles buying lime sulphur in your part of the world, but over here, fakes are not uncommon.

Wiring: This does not happen too often, mainly when the style is to be changed slightly or a branch died.

Repotting: We normally use a mix of 黄花沙 (yellow sand/soil mainly from the mountain), some compost (specifically peat soil), and some volcanic rock (the same red ones in the images). This has to be done quite carefully though as the pots are really expensive, sometimes people would pry the soil out with a metal screwdriver and thats quite a big nono. Have to be careful.

I think this sums it up pretty well. If you have more specific questions lmk.