The trump is Spade.

1) Which card do you lead from ♥Q1082?

With no 3 cards sequence (full or broken), lead the 4th best card if you have at least 1 honor in that suit. If you decide to lead from a 3 cards suit headed with an honor, lead your lowest card. When you lead your lowest card lead promise an honor also when lead against trump.

2) Which card do you lead from ♥QJ72?

Against trump, you lead also from a 2 cards sequence.

Question Number 3 - 5:
The trump is Spade. Your partner overcalled 1♥ and you want to lead to his suit.

3) Which card do you lead from ♥Q72?

From 3+ cards headed with an honor, lead your LOWEST card. When you lead your lowest card, you promise an honor (but no sequence), also when against trump.

4) Which card do you lead from ♥972?

From 3+ cards with no honor, lead your 2nd high card and later follow with the 9 or the highest card, so that partner will not think you have a doubleton.

5) Which card do you lead from ♥A72?

Never underlead an ace when you defending against trump. Meaning, don’t lead a low card when you have a suit with an ace. It's fine to do it when against NT, as when against trump, declarer might have a singleton in that suit, and might take this trick with his King and later ruff your ace.

6)

What will you lead?
(Best answer score: 5 points)

This is a hard question. You have 10 points and your partner surely has 10-11 or so for their 3♦ bid.

So, what do opponents do in 4♠ with maximum 20 points?
Clearly, they are both distributional, upgrading their hands for either longer trump or shortness in your (and partner's) suit (or likely both).

That means they likely plan a cross ruff play. So, the best defense is to lead a trump and play another trump in any opportunity to minimize declarer's ruffs.

This could be the full hand:

You can see that with any other lead, the declarer can cross ruff and lose no more than 2 Clubs and 1 Spade. But if you lead ♠A and another Spade (or low Spade, and later ruff a Diamond with the ♠A and lead another Spade) , the declarer will not be able to ruff all his hearts in the dummy and will have to lose also his 4th Heart