Hi,
To be very honest - I don't think crawlers are looking at the way you structure your url's. In my opinion these 3 options are equally valid and it depends on your personal preference how you want to organise it. Also think about your reporting needs - it's very easy in Analytics to put filters based on folders (or to use the drill-down reporting)
What is more important is how you make this information accessible for the users - which is completely unrelated to the url.
Like Bryan mentioned - it could be useful to have a support section on your site - regrouping all the support documents for all the products on your site. Again - this could be done regardless of your choice of url's.
To determine the importance of a page crawlers are mainly looking at two things:
- how many links does this page get (both internal and external)
- how many clicks do I need to get from the homepage to this particular page
The relevance is also determined by factors like appearance of keyword in url, H1,...etc all the basic stuff - but these would again be identical for the 3 scenario's you propose.
Hope this helps,
Dirk