Question about franchise mode / progression

So i see there are some 18-20 year olds that are undrafted in the minor leagues in roster edit. Do they go to get drafted again or do the 19 and 20 year olds go to free agency once they age out of the minor leagues? like if i start a franchise will i see them in the draft? also does anyone know what typical progression is? like if there is a top 9 F with high potential accuracy does he get to say 85 overall? or is all based off his stats? trying to edit players so the league plays out to my liking. also if someone is 80 overall and has a high potential accuracy but low potential range say AHL top 6 F but they are 80... do they decrease rapidly?