Holly mamma! Lots of myths!
I've poured a ton of concrete, and like Al, rebar is the ticket! 1/2" rebar every 12", both ways, tied together! With rebar it doesn't move! I don't pour with wire mesh anymore, nor will I pour with the fiber mesh! Both are a joke IMO! Yes, it will crack, but it damn sure wont move!
Unless you are planning on parking something stupid heavy on it, use 2x4"s to form it, a good 3"s of sand, which will compact with the weight of concrete on top of it, giving you 4"s of concrete should be plenty. If you are really concerned, use rebar and order some 4500lb mix, standard is 3500lb, side walks and most drives, this will give you a lot more strength per sq ft without having to go thicker and only cost about $5 more a yd.
As for trying to screed 19', I've done it, but certainly wouldn't do it again! Set it up for two pours, but do it one. Build a form down the center of the drive, garage, with notches over the rebar or wire mesh, then pour one side. By the time you get that down it should be fairly firm, slump 6 or so, then pull the center form and pour the other side to match. When you get to pulling that much mud it will wear you out too fast! It's just not worth it! Then trying to keep it even and smooth, well, good luck! Like I say, been there, done that! It's not something for a small crew! Make it easy!
As the others have said, pull the wire or rebar, constantly! Even if you've pulled it, pull it again, because you may have stepped on it! Always pulling rebar when you pour!