1. I would absolutely want to develop it myself....all I have to do is find the time to develop all that I would like to.
2. Personally I like to see at least 10K worth of OVT searches, although that's not an absolute. Once you see that, you know there is interest in the words, not only at OVT, but also at the other engines like Google, MSN and Yahoo.
Remember though that OVT searches are those that you pay for....if you intend to develop, then actually use OVT, you must also check the key words on OVT and see what users are paying for them...if they are going for $ per hit, you may think twice about developing that site because of the high competition. That will probably also translate to large numbers of Google results. All those really show you is there are a lot of sites related to your keyword.
3. Guess what? Google results only do you good if you can get your site into the top twenty, and preferably in the top ten. It doesn't matter if there are 50 or 50 million results. The only way you are going to do that is with some good SEO (Search Engine Optimization) and getting a bunch of incoming links to your site (preferably sites related to your topic and with high PR.
Hope this helps with your questions.