First time CD buyer. Looking for perspective from those who have been and done.

Hey guys, so im looking at building a CD ladder for the first time, but im wondering how CD's affect taxes? Does interest earned count as earned income? What if I roll any earnings back into other rungs of the ladder and never touch the money? Also, how did you all narrow down the options to find the best APY's? Im noticing at this time apys are around 4.2-4.9% so, should i just use that as an acceptable range? Just looking for thoughtful opinions, as i know not one answer is ever the answer. Thanks guys!