On descents you do not want to remove your feet from the pedals as putting your feet back into a 300 rpm blender can be really dangerous... and stupid.

You want to soft pedal and maintain a little input so that you don't end up spinning uncontrollably and once you can do that descents will get easier and faster... I know guys on geared bikes that have trouble keeping up with me on descents since I can spin the 79 gear inches on my Pug at some good speeds and still maintain good control.

All my fixed gear bikes also have brakes as you can't spin at 160 plus rpm for long periods and if you have to stop / slow on the way down that brake will become your best friend.

For general riding I like gearings on the mid to high sixties as the wind never stops blowing here, nothing is really flat, and I do have some rather decent climbs that I can do pushing nearly 80 gear inches but I do try and be kind to my old knees which have not blown up yet.