> 1) Will Google penalize us for getting rid of (deleting) those junk pages.
Google already advised Pandalized webmasters to get rid of junk (noindex/remove/move to another site).
> 2) If you can't find the info from a tool, use Google Analytics for Landing Pages. If nobody landed in the last year, the links can't be worth much.
Google finds very large sites highly suspicious, and subdirectories with many pages, too.
> I think that people who have been testing Panda solutions would agree to deleting/no-indexing as much of the site as possible... or even starting over.
Everybody has to find the right balance between destroying the building. If you kill 90% of your site's traffic all at once, and then rebuild, you could lose all that traffic while you rebuild.
How long is that going to take?
Slow and steady building and rebuilding is most natural and least suspicious to Google.