The second half of the game really was a nice surprise. Had I known how I'd have to re-trace my steps, I'd have played the previous levels a lot differently.
Rogues rake in LOTS of cash monies. If you're looking to collect all the medals, rogues will bring in the extra monies you need to buy all those chickens...
Was able to beat world 1-3 with only one death. It takes a while...but if you have one of your animals jump into the spikes...then have another jump atop their bones...you can 'walk' the bones toward the gold acorn.
Have your animal just about walk off the left side of the bones, then quickly walk back to the right (might have to jump to save yourself).
Was able to finish with 26 animals alive.