Sounds like I have approached this the wrong way/order. I have built a very early prototype (early MVP). I was going to try promote this and gain feedback. What I should have done earlier is test 1 and 2. I have found getting attention and finding people online difficult. Is face to face better for initial evaluation? Is gaining traction easier once you know your target market?
"Wrong" sounds too strong as many startups proceed this way and some people (like Seth Godin yesterday) more or less suggest this approach. However I'm strongly convinced that verifying problem before solution can bring extra value and inspiration for relatively small effort. If I was you I'd proceed in that order: 1. Talk to at least 10-20 friends&acquaintances about their experiences with job interviews: What's the most difficult (stressing etc.) thing for them? How exactly do they prepare? How much time does it take? What specific information, advice, tips are they looking for? Where do they search? How often do they find it? How helpful these tips are? How strong is their desire to prepare better? And similar questions to deeply understand what is the problem, how they are trying to solve it and how satisfied they are with the current solution. This info will provide you qualitative data that will help you build better survey for online problem verification. These interviews will also probably suggest you online sources for survey respondents (specific forums, communities, Q&A sites etc.) where people searching for such solution are gathering. I guess Quora and LinkedIn might be such places. At this moment the survey will work for you amassing the quantitative data about the problem assumptions. And even more - interviews will help you identify specific keywords related to your service which might be used to gain traffic for the survey and later for the product itself. When you have this you can finally test the solution itself and I guess it'll be better than the initial idea. As a summary: definitely you need to define and understand you target group (who are they? how do they think and feel? what are the best channels to communicate with them? etc.) to bring them solution they need and present it in a way that will be attractive for them. In addition to obligatory ;) stuff by by Eric Ries (Lean Startup) and Steve Blank (Customer Development) you may find "This service design thinking" book inspiring. And in case you would need some specific feedback about your project feel free to contact me via Google+. I'll be happy to help because recruitment field is in my scope of interested. And I've experienced my share of unprepared candidates already :)
Thanks for the further information. I will put these into action and let you know how they work out.