probability that a 7 card hand has one 1 card suit? so like one spade and 6 others amongst the other 3 suits.

So far I got (39 choose 6) * (4 choose 1) to pick the suit that has one card * (13 choose 1) the card of the suit being picked divided by (52 choose 7), however that's not correct.

answer is .8165

How many 7-digit sequences using the digits 0, 1, 2, and 3 using at most three of those digits?

answer is 7984 and I have no clue where to start