How many meaningful English words can be formed with $ESRO$ using each letter only once in each word?

Each of the following questions is based on the following alphabet series.
$A, B, C, D, E, F, G, H, I, J, K, L, M$
$N, O, P, Q, R, S, T, U, V, W, X, Y, Z$
If the given alphabet is arranged in reverse order,which letter will be the eighth letter to the left of the seventh letter counting from the right end?

Select the series in which the letters skipped in between adjacent letters decrease in order.

How many letters in the word $CLIENT$ remain in the same position when the letters are arranged in alphabetical order?

Each of the following questions is based on the following alphabet series.
$A, B, C, D, E, F, G, H, I, J, K, L, M$
$N, O, P, Q, R, S, T, U, V, W, X, Y, Z$
Which letter is seventh to the right of the eighteenth letter from the right end of the alphabet?

Each of the following questions is based on the following alphabet series.
$A, B, C, D, E, F, G, H, I, J, K, L, M$
$N, O, P, Q, R, S, T, U, V, W, X, Y, Z$
Which letter is the seventh to the right of the thirteenth letter from your left?