Soil Amount Heavily Decreased

roll down pot, or add like 1cm lair each week.

Can't be avoided, but filling your pots to the max at the beginning will provide the most room for root growth. Top dressing the pots with a small layer of extra soil as the plant grows can also be done.

Water carefully & slowly in multiple small doses, use living soil (the living biology like bacteria, fungi, insects, worms,... etc will keep your soil fluffy and spongy), add topdressing as food which will leak saponins into the ground, which act as a "glue" making your soil crumbly and fluffy together with the microorganisms, use a watering agent like "Yuccah BAC" or Aloe Vera extract which also works through saponins. Also adding a mineralic/inorganic structural component like pumice or perlite to your soil helps with reducing shrinking of the soil. Technically a substrate made out of 50/50 peat/pumice can not significantly shrink (if the pumice has a chunkier size) because the pumice is persistent and if the peat decomposes it will just fill out the pores that are there anyways in between the pumice...

Just the act of watering is going to pack your pots more. Especially comparing to when it was recently planted and the soil was extra loose. If the roots are covered then it's not really an issue.

Not a lot you can do. Just be careful when picking up and placing pots back down. Believe it or not, I reckon that's where your issue is. You could try add some big rocks at different layers. (Grow stones) or introduce clay pebbles into the soil. And just be mindful when moving not to be heavy handed.