Personally, I wouldn't try to figure out the impact by looking at crawl stats.  I'd be more focused on end results.  Have we had an increase in organic traffic, or conversions from Google shopping since we opened it up, or has either of these gone down?

That's what matters, and is the only real indicator as to whether it was a wise move or not.

Eric,

Unfortunately you're in a very difficult position.  Personally, I would never proceed with a client who can't even define their own audience. They're quite likely going to change their mind often, and if you get involved this early on, will just as likely be overly demanding and play the "needy victim" role.  It's a mess.

Having said that, if you insist that you absolutely must work with them, the best approach might be to choose four, five or six topics you think are appropriate, run them through the Google Keyword tool, export each result set and pass them an Excel spreadsheet with each result set being in a separate tab.  Then, help them understand what the columns mean (competitive, search volume, etc) and let them chew on that data.  Explain that you need them to decide which phrases to go with, but that you can help them refine it down a bit.

Be very careful though to not get sucked into an endless hours vortex!

There's some disagreement in the industry as to whether the pipe symbol or hyphens are best - either way, one of these two would be recommended for readability purposes.  This is especially valid when you've got more than one keyword phrase.

Product Name | Alternate Product Name | Company Name

Whether you include the sub-nav in the site-wide navigation as drop-downs or not, make sure that you also have that sub-nav as on-page links (such as in a side-bar) specific to each section.  So that only that sections page links will then be on all of the pages just within that section, without the drop-down needing to be used. This ensures proper attribution and relationship queues for SEO.

Having said that, this issue is widely debated in the industry.  I've seen arguments on both sides claiming they have proof that one or the other of your choices was better.  Personally, I've always taken the approach that SEO should always be balanced with usability.  So when this question comes up I don't tell clients to kill the site-wide drop-downs.  Instead, I focus on other refinement (like the section by section dedicated side-bar links, and proper breadcrumbs, and in-content links, and so forth).  And that has always gotten my clients solid results.

Regardless of whether they're updated or not, RSS feeds are generating duplicate content and not the original source, so the value is going to be either none, or more likely, less than comments on an original source.  And if you're actually here asking this question, I'd suggest that unless you perform a specific test, in a specific situation across a specific market niche, you're not always going to get the same results.

And unless you're looking for brute force link building, it seems like a poor time expense to pursue these given the dupe-content factor.  And if you are looking for brute force link building, don't rely on this method being sustainable.

Christopher,

I'll add to Pashmina's answer in saying that just like any other data point, I've personally always used data from the Google keyword tool and any other similar "solution" for trending insights only, not for real analysis. Another possibility is in how you use the resource.

If that's the case Jose, then unique content is key.

Jose,

I'm curious to understand why you need a separate unique page for each size.  Do that many people search for particular tire sizes as compared to broader tire related phrases?   Personally I'd think that listing all tire sizes on a single page would be more user friendly.  And it would allow for even more content on each model's page.

The other side of that reasoning is having hundreds of size specific pages that have no unique content other than the size (name for all intents and purposes) would classify those pages as thin content and less likely to have those pages rank especially given that you're unlikely to get unique quality inbound links pointing to most of those.

So my recommendation would be to focus on building up those model pages and not going with unique size pages.  Or, alternately, finding ways to creatively generate a couple paragraphs of truly unique content for every size page in the system.  Anything less and it's duplicate content.