i am just sharing that my blog ( listed n recent blog) was decreased from PR0 to N/A i work a lot but no results and today when i remove all my old gadgets and layout then i see its PR2 with out www and still NA with www also its DF i can approve you if you have relevant niche
Don't worry.. PR becomes N/A when a update is round the corner. About your query, layout has nothing to do with PR.
Indeed, layout doesn't affect on PR. Your PR just downgrading to n/a and this is natural in SEO. No need to worry, keep add quality content and backlink.
I don't think so, since google is now pretty comfortable with flash as well. PR is based on links, and links purely. PR data are exported to the toolbar once in a while, so the toolbar value is based on what your previous efforts were, not on what you are doing right now.
Don't agree 100%. If your site has nicer layout, visitors can stay longer on your site and come back to see the layout -> Better bounce rate -> higher PR .