[KaLiB]

We don't usually measure the weight of the salt to add in when making our own saltwater but instead we use a refractometer/hydrometer to measure the specific gravity (SG) of the water to determine if we have added enough salt. We normally maintain the SG at 1.023-1.025 for fish. If I didn't remember wrongly, you need slightly less than 2kg of salt for a 2x1x1 after adding in sand and rocks so please don't empty the entire pack of red sea salt into the tank immediately or you might make the water too salty.

IMO, it would be better to skip the artificial coral stones as they can be overgrown with algae and look unsightly in the long run. For fish setup, you can consider using a combination of liverocks and coral sand instead. Liverocks provide decoration and they contain a host of beneficial organisms including bacteria to help with biological filtration for your aquarium.

Are you referring to PSB bacteria product by Azoo? If yes, it can be used but IMO, it isn't necessary to dose any form of bacteria if you opt to use liverocks and sand.