5. No, you didn't mis-see the hand, you are pretending you have the queen because you have a 10-card fit. With 10 cards, you can pretend that you have the queen since it will likely appear when you play your ace/king.

5. The next step after your partner's keycard response (assuming the next step isn't your own suit) asks about the queen of trump. Here, you don't want to bid slam without partner having that card since you are also missing a keycard. It's hard to imagine partner control bidding without it, but you've seen stranger things.

5NT. I don't like to bid a grand slam unless I can count to 13 tricks. Here, I know we have all of the keycards, but that only gives me 3 aces and 5 spades plus likely at least two heart ruffs (10 tricks). Partner has to have more than just 3 aces for this splinter, but we can find out exactly what by bidding 5NT. If partner bids 6, we can make another probe and hope that partner makes the decision for us by bidding 7. When we don't ask about the queen here, partner will know that we have the other two keycards plus the queen of spades so partner might be able to count to 13 tricks in his own hand.

Pass. Partner's bid is quantitative, not ace-asking. You have a balanced minimum without a fit, so you want to stop. If partner wanted to ask for keycards, he could have started with a Texas Transfer (see #4 here). If he wanted to know about aces, he could have used my least favorite convention: Gerber.

7. What does 5NT mean? By partnership agreement it should either ask about specific kings or number of kings. Either way, however, it should guarantee all of the keycards unless you have an agreement otherwise. Since you have all of the keycards, either side can now take over on the quest to bid 7. You should be able to count to 13 before bidding a grand slam, so let's try. We have 6 heart tricks, 4 clubs, and two aces. That gets us to 12. How do we get to 13? If partner has long diamonds, we might be able to set them up. Partner could have either king that we are missing. In the absolute worst-case, we might need a spade finesse. Note that since 7NT may also be cold if partner has a king, an advanced-level bid here would be 7 showing a hand that will bid 7, but also has tricks for 7NT if possible.

5. People invariably ask me how to show voids with keycard. My answer: don't. Unless you know for sure that your void is helping, pretend it doesn't exist. This holds doubly for when you have a void in a suit partner has shown. Here, imagine partner has:

 AKJ53  
 AQ62  
 Q73  
 8
 This is a great hand, but slam is missing two cashing keycards. Voids can be very helpful, but (even if you have a method) not all voids are worth telling partner about.