Hint: The first letters of the words are W, E, S, A, S, C, O, T, W, A.

Answer:
Windbreak, eiderdown, sometimes, afternoon, September, carpenter, offensive, telephone, Wednesday, apartment.

Hint: The answer is a whole number less than 10.

Answer: 3.

Checking that 3 works:

    3     3     3     3
    -  -  -  +  -  =  -
    3     2     4     12

    1 - 1.5 + 0.75 = 0.25

              0.25 = 0.25, which confirms that 3 is correct.

To deduce the answer directly from the question, we can multiply throughout by 12,

    *     *     *     *
    -  -  -  +  -  =  -
    *     2     4     12

to give:

   12 - 6* + 3* = 1*

        12 - 3* = 1*

             12 = 4*

              3 = *

As required.

Hint: Say what you see.

Answer: Forest.

[Four EST].

Hint: At each stage a new dot appears at the top.

Answer:
At each stage, a new dot starts at the top, and then goes either clockwise, or counter-clockwise.

Hint: Every word must contain the central letter.

Answer:
Common words: adept, alp, ape, apt, cap, cape, clap, clip, cup, cupid, depict, dip, dupe, DUPLICATE, epic, lap, leap, leapt, lip, pa, pace, paced, pact, pad, paid, pail, pal, pale, pat, pate, pea, peal, peat, pedal, pelt, pet, petal, pi, pica, pie, pied, pile, piled, pit, pita, place, placed, placid, plaice, plaid, plait, plate, plated, plea, plead, pleat, pled, plied, pud, put, tap, tape, taped, taupe, teacup, tepid, tip, tulip, up, update.

All words: adept, aliped, alp, ape, aped, aplite, apt, cap, cape, caped, caplet, caput, cep, clap, clapt, clept, clip, clipt, clupeid, culpa, culpae, cup, cupel, cupid, dap, depict, dip, dipt, dup, dupe, duple, DUPLICATE, elapid, epact, epic, epical, lap, leap, leapt, lept, lepta, letup, lip, pa, pac, pace, paced, pact, pad, padi, padle, paid, pail, pal, pale, paled, palet, pat, pate, pated, pe, pea, peal, peat, pec, peculia, ped, pedal, pelt, pet, petal, pi, pia, pial, pic, pica, pical, pice, picul, pie, pied, pieta, pilau, pile, pilea, piled, pit, pita, piu, place, placed, placet, placid, plaice, plaid, plait, plaited, plat, plate, plated, plaudit, plea, plead, pleat, pled, pleiad, plica, plicae, plicate, plicated, plie, plied, plutei, puce, pud, pudic, pul, puli, put, taliped, tap, tape, taped, taupe, teacup, tepa, tepal, tepid, tip, tulip, tup, up, update, uplit.