The Amozonia or Africana are only color choices, and do not indicate what type of plant will grow best. All AS works the same.
PS, supplies nutrients...that is the "power" in the powersand. It is not needed if you plant on dosing anyways. Many folks use it and are happy, if you want a lower light and lower maintneance tank, AS and PS are the ticket. If you want highlight, EI etc..then just AS is fine.
You can spend a lot of money on ADA chemicals,a nd they do work well. Or you can just by bulk ferts and save money like most folks. You can be very successful either way, one way just lets you be successful with more money in your pocket.
There are some who claim this, perhaps it is more associated with PS than AS. IME, there is no overt spike of any kind associated specifically with AS only. That said, AS will/may have a strong effect on your KH
especially at first. This effect slows after a couple months.
Your move plan sounds reasonable.