I can answer the APRC part but not the rest, sorry. The statement that I was referring to in itself is the same for anyone who has declared an income the year before. There will be a “gross” amount followed by a list of items, deductions, etc. and with the tax to be paid listed at the end. NIA will look at that amount to ensure that it is higher than 2x the minimum salary for that year.
So in perspective, I would suggest you ensure that the money that you are planning to earn during the 3 years is comfortably over 2x the minimum salary (just Google “Taiwan 202* basic wage”). That should tick the “salary requirements” part of the APRC application.