I have a few simple probability questions regarding draws from a deck of cards.

1) If two cards are drawn face down, what is the probability that the second card is an ace?

2) If it is known the first card draw is an ace, how would that change the answer to (1)?

3) What is the probability that 2 randomly drawn cards are both aces?

4) If two cards are drawn from a deck, how many different combinations of the two cards are possible if the order is not considered and if the order is considered?

For (1), I think the answer is 4/51, but do I need to include the probability that the first card is not an ace?

For (2), I think it's 3/51.

For (3), I think it's: 4/52 * 3/51 = 1/221

For (4) - no idea