Random combinatorics

Random sets of distinct permutations, combinations and subsets

Generation of random sets of distinct combinatorial objects:
Distinct random permutations (orders, rankings) of n elements (out of n! possible).
Distinct random combinations of k out of n elements without repetition (out of nchoosek(n, k) possible).
Distinct random subsets (combinations without repetition) out of n elements (out of 2^n possible).
Can force to include the "identity" or "null" element. Resulting set is sorted.