About the water changes, just add the cupramine to the water. I usually do between 11-13 drops per 5 gallon bucket and that worked well for me. You'll have to test a few times to see what works best for you.
As for keeping the ammonia down, yes water changes will do that. You may have to do it every 2-3 days for a few weeks but it will eventually cycle and establish. On a positive note, cupramine is very gentle on biological filtration.
In the mean time, I would definitely get an ammonia alert. I also just noticed you wrote you had the API copper test, assuming you don't have a seachem copper test kit? It'll work but the trouble is it goes from 0-.25-.5-1.0-2.0, etc. You will want the seachem copper test kit with cupramine because the dosage is so much smaller than chellated copper. It reads in .025 increments.