LRT can identify if it's a blog or directory but not like that. You can edit them though. You could check their trial out, see if it fits your needs.

You'd still want the other pages of the site to show up on Google so it defeats the purpose of just having the homepage show that, either way, it will be complicated if I pushed for that and forced redirects, so I would just make it simple and introduce an unblockable popup that logs IPs for that instead of making that verification page the actual home page. That way, I get to keep my optimized homepage and you can make the most of popups like introducing sharing/signups etc.

For easy niches, Ive made these things rank in the past but it's been a long time since I've worked on a site that still use verifications that way. It might be harder this time, but if it's easy enough, optimizing that page with some more content and targeted meta details should still work like a charm.

Look at Google Trends, Quora, Yahoo Answers, keyword tools that get from Google Instant are also good.

Find forums. Look at Reddit (add /top/?t=all at the end to check out the most popular posts)

You need to test it and see what happens. Most of the times I've done this, nothing really happened. As long as everything is pretty much intact and the URL didnt change

Link Research tools or URL Profiler

Heck, even scrapebox can do a bit of the analysis