Defence problems: What to discard?

More tricks are probably lost due to making the wrong discard than any other reason.

It is safe to discard a club as declarer has already ruffed clubs. Instead keep length with dummy http://tinyurl.com/yclb727f

Normally signal with a high-ish card to encourage, but here that may waste a trick, so signal with a low card in another suit http://tinyurl.com/ybul6vv9 Your partner should realise you should have some high cards, switch to a heart to defeat the contract.

What should West play on the 3rd club. East discarded a low heart, so should NOT have A or K – declarer has those, so your QH should be protected! https://tinyurl.com/2nvwgjn2

Everyone made 3NT, but is should be defeated. What should East play on the 2nd spade? What should East discard when the clubs are played? https://tinyurl.com/yc833xcj