Depending where you have your Alkalinity, if it is dropping below 8dKH then you can start the dose at the 2ml per 100L, test and adjust from there. If you are planning on adding corals then yes that will help increase the dose somewhat.
Your aptasia (as seen in first pic above) would be the first concern before placing many SPS or LPS corals in your tank. We've all battled aiptasia (or most of us) but that would be my first objective to eradicate those. Your question as to whether you can place corals in the tank or not is more dependent on your willingness or commitment to maintaining consistent levels. I see you've got a clam in there already that counts as a "coral" lol