You want to save money in this hobby? Boy are you in for it.
To save yourself $15 try ordering the fertilizers separately, rather then as a package.
The bottles are nice but do you need a fancy bottle?
Put that money towards a powerhead to circulate your water.
If your interested in DIY CO2, that money can go towards that at well.
Keeping your goals in mind, you do not need to be very ambitious when adding fertilizer.
Moderate lighting, slow health growth, no additional CO2, most tanks you describe, space the day for changing water further apart and keep the water parameters stable, over the longest period of time, before disrupting them with a water change. That means maintaining 5-10ppm of NO3 while maintaining PO4 and K+ levels relative to NO3. There are several options of how to maintain them at those levels, with fewer water changes and under moderate light. Add CO2, then more growth > more nutrients > more frequent water changes and I'm going to stop here. More frequent water changes are the best way to maintain stable water perimeters - it's all about the CO2.
Add GH booster (K2SO4 and MgSO4 will suffice) every week,
add KNO3 and KH2PO4 one day,
add CSM+B the next day.
Wait a week or so and start again, GH, NPK, trace.
Just remember when using fertilizer in these low ranges, supplementing NPK is only effective when it enhances growth.
When we dose less fertilizer then the plants need to maintain healthy growth, we experience problems.
I'v seen optimal water flow in natural environments close to 2 knots.
You need a filter that is appropriate for your tank. I'm not sure that yours is, yet with healthy growing plants, I'm not sure it isn't. a number of planted tanks have flow rates that cycle 10 gallon tanks, 10 times in an hour. Small prop style powerheads are a great addition to a filter. Your flow will not need to just come from the main filter, just facilitate it's effectiveness.
More on light by Hoppy;
What some bulb colors look like;