If you have to lose time, the best way is go low and slow.
Correct. Losing time is, in effect, holding. Check out the best holding altitude and speed in your FCOM...
In my machine, RTA is a WOFTAM. The descent speed will remain the FMS speed for the Cost Index. If you don't have a lot of time in the cruise to fly at a low or high speed to adjust the time, it won't work. Adjusting the Cost Index to achieve the Feeder Fix time is king. It will also reduce the times when someone is cruising at Vmin then suddenly accelerates to warp speed as they start descending. Us: "Err, Centre, isn't that 737 ahead supposed to be behind us?" ATC: "XXX, will you be able to make your time?" Them: "Yessir, we'll be descending at 550KIAS!!", which obviously doesn't work. I exaggerate, but this has happened to me on a few occasions.
On my jallopy, FMS winds are loaded by the crew from the computerised flight plan (or NAIPS SPFIB).
The biggest pain is that the ETAs on my box aren't shown in decimal minutes (until on the last segment to the Feeder Fix). It would make life so much easier it they were.