You should bid as low as possible to leave bidding room for opener. That suggests that 1 diamond is the best response in the first hand (unless it is artificial but forced and shows a "bust" as some players bid), 1 spade is a close second best, and TWO clubs is the worst, because it "jumps" the bidding when opener may have only a three card suit.
Some partnerships give preference to the majors and say that you should respond one spade with ANY four carder, even 5432. If partner has a four card spade suit, say, KJ76, s/he'll want to play in spades with a 4-4 (eight card) fit. Worst case, it will be 9876, but to have the "worst" four cards on both sides is pretty rare. With a 3-card spade suit and a 3-card club suit, partner may call 1NT to your 1 diamond or 1 spade bid, which your 2 club response precluded.
In the second hand, the lowest reasonable response is 1 heart, four card major. Again, even with 5432. If the opener has four hearts s/he'll raise hearts, with four spades, bid one spade; with 3 spades, 3 hearts, 4 diamonds, 3 clubs, s/he'll bid 1NT. But you're bidding 1NT takes most of these options away from partner.