"My collegae says don't use www.exactkeyword.org, because we aren't a non-profit organizaton and we can't garantuee we won't lose our rankings over the next 3 to 4 years. He would recommend going with the available www.exact-keyword.info."

IMO exact-keyword.info is the spammiest type of domain.  I would not even click into one from the SERPs.

If you use a .org the more famous you become the more traffic you will lose to the .com (because so many people simply assume that any important site is on a .org.  (maybe where you are - if you are playing for local traffic the .nl would be fine).

You obviously have a few people working on this project and have spent a lot of company time working on this.   I would simply find who owns exactkeyword.com and be willing to pay good money for the domain.   Or, I would find a great dot com without a hyphen.

If you have a great staff working on a great site go get a great domain.

I started a site ten years ago with a hyphen in the domain.  The domain without the hyphen was owned by a domainer.  The harder I worked the more traffic he received when my customers typed the domain without the hyphen.

I finally paid a lot of money to get the domain without the hyphen.

On another project I had a domain with a hyphen.  Within a year I was able to obtain the domain without the hyphen in an auction.  When I redirected the hyphen domain to the non-hyphen domain the rankings went up immediately.   Immediately.

I used to have sites with hyphens... and all of my hard work was enriching the guys who owned the domains without a hyphen.  The harder I worked to make my site popular the more they enjoyed it.   I finally gave in and paid big bucks to get those domains.

So when you are workin hard to make Rons-KickAss-Site.com  AND RonsKickAssSite.net  huge successes they guy who owns RonsKickAssSite.com will be smiling as lots of your customers land on his spammy site and click ads to sorry domains.  Not a good customer experience and not good for your wallet - because the people who remember the name of your site well enough to type it in without a hyphen were probably going to buy something. Nice you just lost that $2000 sale to someone else - and he thinks you went out of business.

So, spend a little more time coming up with a kickass domain or be willing to spend some money to get the domain that you want.  Because if you own RonsKickAssSite.com I doubt that anyone is going to look for you at Rons-KickAss-Site.com

Here's a couple of quotes from Rand's post..... at http://www.seomoz.org/blog/how-to-choose-the-right-domain-name

and while directing traffic to a .net or .org (as SEOmoz does) is fine, owning and 301'ing the .com is critical.

Both hyphens and numbers make it hard to give your domain name verbally and falls down on being easy to remember or type.

When you say...  "White Paper"... does that mean publishing it in .pdf?  I would not do that unless you need it in that format for controlled printing or distribution.

Otherwise I would publish the paper on a standard webpage because they are easier to optimize, easier to monetize and fit into the format of your website.

If you do go with PDF, remember that you can optimize it to be seen in the SERPs, include links to your website and that many shopping cart links will work  within a PDF.

This really isn't a direct answer, but it is how I approach the problem.

The difficulty with long-tail keywords is that there are SO MANY OF THEM.   It is impossible to target all of them.

Building specific landing pages for each of them would be really time consuming if done properly with content and would make a very spammy site if done quickly.

So, what I do is draw upon my knowledge of the products or topics that I am targeting and write the following types of content.

1. The questions that people most frequently ask.

2. The things that they don't ask but need to know to be succesful

3. The things that would surprise them - like misconceptions, extremes  and WTFs.

If you have a lot of #1 content on your site it will pull in a lot of these long tail keywords.  These pages should be substantive in length and detailed in information.  That will put a lot of diverse words on the page that will match many long tail queries.  These will pull in traffic.

Content in the #2 and #3 category, if written with substantive length and detail, will also pull in a lot of long tail... but in addition, these are the types of pages that people will link to, share and recommend.  They are the astonishment topics that people enjoy and share.  In general, these are some of the most successful pages on my websites.  My site is mostly factual and serious topics... but I get tons of traffic on these types of topics through links on reddit, stumbleupon, cracked, FB, etc.