Hint: Consider one digit at a time (you want to draw a tree diagram). The first digit has four combinations as does the second (because you can have 0 in the second but not the first). Complete this for the 3rd, 4th, and 5th digit and note that each digit is independent.
In probabilities and frequencies (or counts) independence means you multiply each digit combination to get total combinations.
Hint for 2: Remember that even numbers must end in a 0, 2, 4, or 8 (last digit).