Yes, P and K are your other two macronutrients that are required for healthy plants.
And the chart probably seems like a lot of dosing because the Seachem products are mostly water.
Dry fertilizers are the way to go, if you want to save money.
I second darkblade. I think eventually you will want to go with dry ferts and make your own solutions. The seachem products are not bad, but getting your own dry ferts is a lot more cost effective down the line and you won't be paying for water.