LEARNING CENTER

2. We're missing the A and Q. If the leader or right hand opponent has both, then it doesn't matter which you choose. If the honors are split, it's right to play for West to hold the Q since leading low away from an ace is a big no-no against a suit contract. 

4. Against an excellent opponent, this might be a true guess. Against most players, though, East (RHO) is likely to cash the ace if he has it. We also have the inference that West did not lead a diamond and might have if he had a suit not headed by the ace. 

Lead towards dummy and play the J. Again, if your LHO is an expert, this is a guess. If your LHO is a normal player, however, he will at least consider winning the ace (if not flat out playing it) if he holds that card. Playing the jack assumes that LHO will sometimes play the ace. 

Win, lead a spade to dummy, and play the J, intending to play the A and K. We know the odds favor playing the A and K, but why not introduce a little temptation for East? If he holds Qxx, he might cover. This is just another trick to try to add that small extra winning chance.

Low from hand to the K, then a low heart ducked. You need to find Ax in either hand. West chose a somewhat random looking lead (not a sequence). A heart would have been as attractive, so we might guess that they didn't lead a heart because he holds the ace. 

Lead the J or lead the 10 (and play the honor). You want to try to induce your opponent to cover (just like question 4). If you cash an honor first, you'll make it less likely that they will do so. If you know which way you want to finesse (becuase of other information in the deal), then you would typically cash an honor first before taking the finesse to pick up a singleton honor.