The Polywebs have a thicker coating and feel waxy - it is this that gives a more mellow tone and less string squeek. The Nanowebs have a thinner coating and sound and feel close to normal (uncoated) strings but have the capacity to last much longer tonally, ie they keep their brightness for significantly longer.
Interesting post. I have always allowed a bit of excess (in line with your suggestion) when winding and always put a right angle bend in the string for going through the post. The strings that usually break at this point are the 2nd and 3rd which are under a lot of stress from altered tunings, but that is what I would expect. If any of the other strings go, it is usually at the saddle, though I do get breaks on the 2nd and 3rd here too.
If I gigged really often, I would use D'Addario and change them each time, Elixirs would be too expensive to do that. However, I don't gig more than about once every month (on average) so I use Elixirs for the longer lasting tone, but always change for a gig to minimise string breakage on stage.