For this particular interview, I described my level of experience, and there were less than 5 questions specific to the job. However, each interview may be slightly different. Here is what I usually experience for a Validant contract:
First of all, I will speak to my primary recruiter to discuss whether the job is the right fit for me and, most importantly, whether the money will be the right rate for me. Validant discusses money first. That is very important! Then I will speak to a recruiting manager for that specific client. Finally, I may or may not speak to the client directly. All this is performed via phone. 90% of time I will not need to show up in person. I have only had to show up in person for one interview in over 3 years of contracting with Validant. The phone interview with the client is usually less than an hour long, but if I need to show up in person, the in-person interview may be up to 4 hours long. Skype has not been required.
Please note, if you are asked to show up in person, which there will only be a 10% chance of this, negotiate that both hotel and travel expenses are covered. For one particular contract, hotel was covered, but mileage was not covered (I drove to the site for it was only a few hours away).