I was under the impression that when cruising in tailwind conditions, one would delay descent in order to benefit from the increase groundspeed as an early descent would minimise the tailwind component as you descend.
No. To do this, you would have descend faster (subject to ATC approval) and might need speed brake too. By delaying the descent, you are consuming more fuel the longer you stay in the cruise, compared to idle thrust descent.
Also when cruising in headwind conditions, an early descent would reduce the overall headwind component with altitude and allow you to increase your groundspeed whilst increasing fuel efficiency.
No. As it means you will have to descent with "some thrust on" to prevent getting too low.
The most efficient descent is an idle thrust descent without speedbrake (at an ATC approved speed - 280 knots in Australia).
A descent is basically a glide. Therefore, you will glide further with a tailwind so commence descent earlier. Opposite with a headwind.