wads are better then cornmeal filler when you shoot small charges, you need a way to seat the ball in the chamber, ie, you have something filling the space between powder and bullet because no matter the rammer, it can only push the bullet so far into the chamber.
as far as accuracy, some guns have more preference then others. iveseen competitive cas shooters say "no difference whatsoever" so its what the gun likes.
me, i dont use wads yet. didnt feel like spending 20 bucks on a wad punch set, and i dont feel like paying 14 dollars for a bag of premade wads through the mail. thats a boxof bullets dang it.
colt proved over and over that chainfires come from 2 things, poorly machined chambers and poorly fitting round balls. however, we now know that overly long nipples can make a chain fire because the possibility the caps will hit the recoil shield under recoil and go bang.