Yes
&
Yes
Remove livestock (to a suitable large bin with part tank water, part tap ... I usually aim for ~50% water change, drain off tank water as a first step so quality is at its best)
Remove hardscape etc
Remove substrate
Add Tropica Growth Substrate
Add fine gravel, aquarium soil at as upper layer (I assume you’ve watched the many videos on Tropica website demonstrating GS)
Replace Hardscape
Plant
Set up filter etc
Run for 24hrs or so, check for ammonia (I find Seachem Ammonia Alert works well and provides continuous monitoring - just perform a water change as soon as there is measurable ammonia and even sensitive livestock will be fine)
Return livestock
Of course there are other ways to do this (but you cannot “pour” the GS through water without significant issue - do a sample test in a glass of water) but I find this method keeps livestock safe
Note depending on fish, I may keep shrimp separately
Process for fish removal etc is nicely shown in this Filipe Oliveira video