i would lead A in both cases about case 2 , LHO is an aggressive bidder he heard his partner bid 4s and then raised to 6s , so i guessed LHO have not so solid spades( SAY KJxxx spades) and another solid minors suit such as Diamond Aqjxx) . LHO thought his partner have some spades high cards (A is very likely) and also hoped his patner had an ace in heart and at least a king in clubs), so that he can get 12 tricks if the diamonds finnese was on. (His most likely shape is 5152). The best way to defeat this contract is to lead clubs ace either to find partner to have clubs kings or to avoid the endplay. If you lead passively, you are very likely to be endplayed.(a stripe squeeze )