Rural myths, surely? Each in turn:
My cattle don't lie down when it's going to rain. They lie down at night, or when they feel like it. Don't know about other people's cattle.
A very large, fat or pregnant sheep can have a lot of trouble turning right way up. Others can get up fine.
Guinea pigs & penguins -- myths, though it's a shame about the penguin one...
Duck's quack: never tried it, but don't believe it!
An ostrich's eye is very much bigger than a human's, perhaps bigger than any other land animal's, and probably a good bit bigger than a hen's egg. But it's nowhere near as big as its own enormous egg! It couldn't lift its head with one, let alone two! (A peregrine falcon, weighing perhaps 1 kg, has eyes as large as a human's, and each as large as its own brain).
I believe cheetahs can retract their claws a little, but not fully as other cats do.
Bats turn either way, or up.
Elephants can't jump, as their legs can only just take their weight even without a shock. They walk or run with no more than two legs off the ground at once.
They don't have four real knees. Their bones and joints are the same as any other four-legged animal. In a horse or dog (which both walk on their toe-tips), the front "knees" are actually the wrists. The true knee on the rear leg (called the stifle) is high up near the groin, so isn't obvious. The joint on the rear leg which looks like a backward knee is called the hock and is actually the same bones as our ankle (or a bird's "knee"). Bears and badgers and some others have their hocks and wrists on the ground.
However, elephants have their joints further down their legs than other animals (because they don't gallop), so their stifle does look more like a knee. Their hock is low down and is straightish, so it isn't obvious.