Just got chance to try both methods
First tried zooming in the audio editor but at full zoom the ruler showed the same number at two marker points
Perhaps an area in the audio editor which shows the start and end point location in samples is needed as found in soundforge and other audio editors, this would make precise editing easier. Even better would be to have the ruler show bars and beats and be able to snap the locators to them.
The second method (mix down to individual tracks) worked but the shortened rendered audio files were larger than the originals (probably the bit rate or sample was increased). The 4 shorter audio tracks are now taking up around 30 percent more space ! 