Yeah, this page should return a 404 status code as a 404 page, not a 200.  Otherwise search bots (like Googlebot and Roger) will think this is a regular page on your site, and as such this page could appear in search results.

Go to your Keywords tab, and select that single keyword, Go to the Keyword details tab, and select "Auction Insights".  This will give you a bunch of useful information:

• Impression share: How often you ad shows up
• Avg. position: The average position of your ad when it does show up
• Overlap rate: You can see how often your ad appears vs. other advertisers
• Position above rate: How often you're ranking above other advertisers.
• Top of page rate: How often you're at the top of the page (vs. the side).

So if your average position is already between 1-2, and your impression share is high, raising the bid probably won't do much.  However, if you're not at the top of the page much, or your impression share is lower, you might be able to get more clicks by raising the bid.

Sure, 10,000 people is enough to run a retargeting campaign.

You might try bringing up the bid to get some more impressions and see how it goes.  100 impressions isn't enough to tell much of anything.  Retargeting does tend to have the highest ROI of any display advertising if you target it properly.  Since the users in your retargeting list are more likely to convert on your site since they've been there before, you can tolerate a higher CPC with retargeting as compared to other display campaigns.

Are you segmenting your retargeting lists into many smaller lists?  You can split your lists into users that have made it further down your conversion funnel, and bid higher the further they've made it down the funnel already (e.g. visited a subscription page and left, or added items to a shopping cart and abandoned it).  If you're using Adwords and Google Analytics, you can do this easily with Google Analytics Remarketing, and retarget any visitors on your site based on things like time on site, pages they've visited, and custom events and goals they've accomplished (or not accomplished).

I'm taking this as comparing Adroll vs. Adwords as an advertiser... if you mean as a publisher, then ignore my answer.

First, Adwords has all sorts of different display advertising, Adroll is all retargeting Advertising.  I prefer Adwords because it's completely self-service, and I can see all the data and statistics for my placements.  You can see a lot of stats in Adroll, but they don't display conversion stats in the interface for your specific placements.  Also, with Remarketing Lists in Google Analytics, I can get pin-point remarketing based on custom events and goals within Google Analytics.  You can duplicate a lot of this within Adroll, but it requires communicating everything with your reps.

With Adroll you'll get some reps who will help you optimize your campaigns, and with Adwords, if you don't already have reps, you'll be on your own.  Adroll has a further reach than the Google Display Network, so your ads can reach other display networks, as well as Facebook.

Where I work, we use both to maximize our reach!

When looking at conversions I usually look at my Conversions > Multi-Channel Funnels > Top Conversion Paths report.  Here, if you select a Primary dimension of "Source/Medium", a Secondary dimension of "Keyword Path", and set an advanced filter for Source/Medium containing "organic", you should see all the conversion paths that involve an organic keyword.