Hi chee how,
and welcome to the forums
A good question you have, a bit broad though. Surely others will extend/correct my answer.
1) I see the basic skills like this
(i) racket skill (grips, various strokes)
(ii) footwork (posture, footwork patterns, rythm)
(iii) tactics (how to build up a winning situation)
2) Use a heavy racket, a squash racket say, or a badminton racket with the cover on while making badminton-like stroke moves when watching your favourite TV series
3) This one I really do not know, I believe it is difficult to be accurate, difficult to have maximum power and extremely difficult to have accuracy and maximum power simultaneously
4) What I interprete as power on badminton court derives from the following (among other things…)
(i) correct technique
(ii) muscle power, mainly legs, abs, wrist and fingers
(iii) flexibility (allows explosiveness of movement)
So to train power, one should try to improve (i)-(iii) somehow.
This is just my two pennies’ worth.